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Sample records for myelin oligodendrocyte glycoprotein

  1. Structural insights into the antigenicity of myelin oligodendrocyte glycoprotein

    PubMed Central

    Breithaupt, Constanze; Schubart, Anna; Zander, Hilke; Skerra, Arne; Huber, Robert; Linington, Christopher; Jacob, Uwe

    2003-01-01

    Multiple sclerosis is a chronic disease of the central nervous system (CNS) characterized by inflammation, demyelination, and axonal loss. The immunopathogenesis of demyelination in multiple sclerosis involves an autoantibody response to myelin oligodendrocyte glycoprotein (MOG), a type I transmembrane protein located at the surface of CNS myelin. Here we present the crystal structures of the extracellular domain of MOG (MOGIgd) at 1.45-Å resolution and the complex of MOGIgd with the antigen-binding fragment (Fab) of the MOG-specific demyelinating monoclonal antibody 8-18C5 at 3.0-Å resolution. MOGIgd adopts an IgV like fold with the A′GFCC′C″ sheet harboring a cavity similar to the one used by the costimulatory molecule B7-2 to bind its ligand CTLA4. The antibody 8-18C5 binds to three loops located at the membrane-distal side of MOG with a surprisingly dominant contribution made by MOG residues 101–108 containing a strained loop that forms the upper edge of the putative ligand binding site. The sequence R101DHSYQEE108 is unique for MOG, whereas large parts of the remaining sequence are conserved in potentially tolerogenic MOG homologues expressed outside the immuno-privileged environment of the CNS. Strikingly, the only sequence identical to DHSYQEE was found in a Chlamydia trachomatis protein of unknown function, raising the possibility that Chlamydia infections may play a role in the MOG-specific autoimmune response in man. Our data provide the structural basis for the development of diagnostic and therapeutic strategies targeting the pathogenic autoantibody response to MOG. PMID:12874380

  2. The myelin oligodendrocyte glycoprotein directly binds nerve growth factor to modulate central axon circuitry

    PubMed Central

    Mei, Feng; Greenfield, Ariele; Jahn, Sarah; Shen, Yun-An A.; Reid, Hugh H.; McKemy, David D.

    2015-01-01

    Myelin oligodendrocyte glycoprotein (MOG) is a central nervous system myelin-specific molecule expressed on the outer lamellae of myelin. To date, the exact function of MOG has remained unknown, with MOG knockout mice displaying normal myelin ultrastructure and no apparent specific phenotype. In this paper, we identify nerve growth factor (NGF) as a binding partner for MOG and demonstrate that this interaction is capable of sequestering NGF from TrkA-expressing neurons to modulate axon growth and survival. Deletion of MOG results in aberrant sprouting of nociceptive neurons in the spinal cord. Binding of NGF to MOG may offer widespread implications into mechanisms that underlie pain pathways. PMID:26347141

  3. Detection of Autoantibodies Against Myelin Oligodendrocyte Glycoprotein in Multiple Sclerosis and Related Diseases.

    PubMed

    Spadaro, Melania; Meinl, Edgar

    2016-01-01

    Autoantibodies against myelin oligodendrocyte glycoprotein (MOG) occur in a proportion of patients with different inflammatory demyelinating diseases of the central nervous system, such as childhood multiple sclerosis (MS), acute disseminated encephalomyelitis (ADEM), and neuromyelitis optica spectrum disorders (NMOSD). We describe here in detail a sensitive cell-based assay that allows the identification of autoantibodies against MOG in serum. PMID:25814289

  4. Damage to the optic chiasm in myelin oligodendrocyte glycoprotein-experimental autoimmune encephalomyelitis mice.

    PubMed

    Herrera, Sheryl L; Palmer, Vanessa L; Whittaker, Heather; Smith, Blair Cardigan; Kim, Annie; Schellenberg, Angela E; Thiessen, Jonathan D; Buist, Richard; Del Bigio, Marc R; Martin, Melanie

    2014-01-01

    Optic chiasm lesions in myelin oligodendrocyte glycoprotein (MOG)-experimental autoimmune encephalomyelitis (EAE) mice were characterized using magnetic resonance imaging (MRI) and validated using electron microscopy (EM). MR images were collected from 3 days after induction to remission, approximately 20 days after induction. Hematoxylin and eosin, solochrome cyanin-stained sections, and EM images were obtained from the optic chiasms of some mice approximately 4 days after disease onset when their scores were thought to be the highest. T2-weighted imaging and apparent diffusion coefficient map hyperintensities corresponded to abnormalities in the optic chiasms of EAE mice. Mixed inflammation was concentrated at the lateral surface. Degeneration of oligodendrocytes, myelin, and early axonal damage were also apparent. A marked increase in chiasm thickness was observed. T2-weighted and diffusion-weighted MRI can detect abnormalities in the optic chiasms of MOG-EAE mice. MRI is an important method in the study of this model toward understanding optic neuritis. PMID:25520558

  5. Structure of the human myelin/oligodendrocyte glycoprotein gene and multiple alternative spliced isoforms

    SciTech Connect

    Pham-Dinh, D.; Gaspera, D.B.; Dautigny, A.

    1995-09-20

    Myelin/oligodendrocyte glycoprotein (MOG), a special component of the central nervous system localization on the outermost lamellae of mature myelin, is a member of the immunoglobulin superfamily. We report here the organization of the human MOG gene, which spans approximately 17 kb, and the characterization of six MOG mRNA splicing variants. The intron/exon structure of the human MOG gene confirmed the splicing pattern, supporting the hypothesis that mRNA isoforms could arise by alternative splicing of a single gene. In addition to the eight exons coding for the major MOG isoform, the human MOG gene also contains 3` region, a previously unknown alternatively spliced coding exon, VIA. Alternative utilization of two acceptor splicing sites for exon VIII could produce two different C-termini. The nucleotide sequences presented here may be a useful tool to study further possible involvement if the MOG gene in hereditary neurological disorders. 23 refs., 5 figs.

  6. Recombinant Human Myelin-Associated Glycoprotein Promoter Drives Selective AAV-Mediated Transgene Expression in Oligodendrocytes

    PubMed Central

    von Jonquieres, Georg; Fröhlich, Dominik; Klugmann, Claudia B.; Wen, Xin; Harasta, Anne E.; Ramkumar, Roshini; Spencer, Ziggy H. T.; Housley, Gary D.; Klugmann, Matthias

    2016-01-01

    Leukodystrophies are hereditary central white matter disorders caused by oligodendrocyte dysfunction. Recent clinical trials for some of these devastating neurological conditions have employed an ex vivo gene therapy approach that showed improved endpoints because cross-correction of affected myelin-forming cells occurred following secretion of therapeutic proteins by transduced autologous grafts. However, direct gene transfer to oligodendrocytes is required for the majority of leukodystrophies with underlying mutations in genes encoding non-secreted oligodendroglial proteins. Recombinant adeno-associated viral (AAV) vectors are versatile tools for gene transfer to the central nervous system (CNS) and proof-of-concept studies in rodents have shown that the use of cellular promoters is sufficient to target AAV-mediated transgene expression to glia. The potential of this strategy has not been exploited. The major caveat of the AAV system is its limited packaging capacity of ~5 kb, providing the rationale for identifying small yet selective recombinant promoters. Here, we characterize the human myelin associated glycoprotein (MAG) promoter for reliable targeting of AAV-mediated transgene expression to oligodendrocytes in vivo. A homology screen revealed highly conserved genomic regions among mammalian species upstream of the transcription start site. Recombinant AAV expression cassettes carrying the cDNA encoding enhanced green fluorescent protein (GFP) driven by truncated versions of the recombinant MAG promoter (2.2, 1.5 and 0.3 kb in size) were packaged as cy5 vectors and delivered into the dorsal striatum of mice. At 3 weeks post-injection, oligodendrocytes, neurons and astrocytes expressing the reporter were quantified by immunohistochemical staining. Our results revealed that both 2.2 and 1.5 kb MAG promoters targeted more than 95% of transgene expression to oligodendrocytes. Even the short 0.3 kb fragment conveyed high oligodendroglial specific transgene

  7. Recombinant Human Myelin-Associated Glycoprotein Promoter Drives Selective AAV-Mediated Transgene Expression in Oligodendrocytes.

    PubMed

    von Jonquieres, Georg; Fröhlich, Dominik; Klugmann, Claudia B; Wen, Xin; Harasta, Anne E; Ramkumar, Roshini; Spencer, Ziggy H T; Housley, Gary D; Klugmann, Matthias

    2016-01-01

    Leukodystrophies are hereditary central white matter disorders caused by oligodendrocyte dysfunction. Recent clinical trials for some of these devastating neurological conditions have employed an ex vivo gene therapy approach that showed improved endpoints because cross-correction of affected myelin-forming cells occurred following secretion of therapeutic proteins by transduced autologous grafts. However, direct gene transfer to oligodendrocytes is required for the majority of leukodystrophies with underlying mutations in genes encoding non-secreted oligodendroglial proteins. Recombinant adeno-associated viral (AAV) vectors are versatile tools for gene transfer to the central nervous system (CNS) and proof-of-concept studies in rodents have shown that the use of cellular promoters is sufficient to target AAV-mediated transgene expression to glia. The potential of this strategy has not been exploited. The major caveat of the AAV system is its limited packaging capacity of ~5 kb, providing the rationale for identifying small yet selective recombinant promoters. Here, we characterize the human myelin associated glycoprotein (MAG) promoter for reliable targeting of AAV-mediated transgene expression to oligodendrocytes in vivo. A homology screen revealed highly conserved genomic regions among mammalian species upstream of the transcription start site. Recombinant AAV expression cassettes carrying the cDNA encoding enhanced green fluorescent protein (GFP) driven by truncated versions of the recombinant MAG promoter (2.2, 1.5 and 0.3 kb in size) were packaged as cy5 vectors and delivered into the dorsal striatum of mice. At 3 weeks post-injection, oligodendrocytes, neurons and astrocytes expressing the reporter were quantified by immunohistochemical staining. Our results revealed that both 2.2 and 1.5 kb MAG promoters targeted more than 95% of transgene expression to oligodendrocytes. Even the short 0.3 kb fragment conveyed high oligodendroglial specific transgene

  8. Myelin Oligodendrocyte Glycoprotein Antibody Persistency in a Steroid-Dependent ADEM Case.

    PubMed

    Polat, İpek; Yiş, Uluç; Karaoğlu, Pakize; Ayanoğlu, Muge; Öztürk, Tülay; Güleryüz, Handan; Kurul, Semra Hız

    2016-05-01

    Myelin oligodendrocyte glycoprotein (MOG) is a candidate target antigen in demyelinating central nervous system diseases, including acute disseminated encephalomyelitis (ADEM), neuromyelitis optica, and multiple sclerosis. It may give prognostic information regarding monophasic or recurrent course of the disease. MOG antibodies have been shown to be positive in high titers during the first episode of ADEM with rapidly decreasing to undetectable limits after recovery. However, persistent MOG antibodies are considered as a predicting factor for multiple sclerosis, optic neuritis relapses, and incomplete recovery of ADEM. Here we report a unique case with persistent MOG antibodies presented with multiphasic ADEM-like attacks. A 6-year-old girl was consulted with encephalopathy, gait disturbance, and oculomotor nerve palsy. Periventricular white matter lesions were seen on cranial magnetic resonance imaging studies. ADEM was diagnosed and treated with steroid. During follow-up, she experienced repeated episodes after steroid therapy termination. We were able to search MOG antibody at the ninth attack. The positivity of this antibody remained. It was thought to be associated with steroid-dependent course, and azathioprine and intravenous human immunoglobulin treatment were added. Patients with persistent MOG antibodies may benefit from addition of immunosuppressant agents, which may decrease the number of attacks. PMID:27244783

  9. Myelin oligodendrocyte glycoprotein (MOG) gene is associated with obsessive-compulsive disorder.

    PubMed

    Zai, Gwyneth; Bezchlibnyk, Yarema B; Richter, Margaret A; Arnold, Paul; Burroughs, Eliza; Barr, Cathy L; Kennedy, James L

    2004-08-15

    Obsessive-compulsive disorder (OCD) is a severe neuropsychiatric disorder with a strong genetic component, and may involve autoimmune processes. Support for this latter hypothesis comes from the identification of a subgroup of children, described by the term pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections (PANDAS), with onset of OCD symptoms following streptococcal infections. Genes involved in immune response therefore represent possible candidate genes for OCD, including the myelin oligodendrocyte glycoprotein (MOG) gene, which plays an important role in mediating the complement cascade in the immune system. Four polymorphisms in the MOG gene, a dinucleotide CA repeat (MOG2), a tetranucleotide TAAA repeat (MOG4), and 2 intronic single nucleotide polymorphisms, C1334T and C10991T, were investigated for the possibility of association with OCD using 160 nuclear families with an OCD proband. We examined the transmission of alleles of these four polymorphisms with the transmission disequilibrium test (TDT). A biased transmission of the 459-bp allele (allele 2: chi2 = 5.255, P = 0.022) of MOG4 was detected, while MOG2, C1334T, and C10991T showed no statistically significant bias in the transmission of alleles. The transmission of the C1334T.MOG2.C10991T.MOG4 haplotype 1.13.2.2 (chi2 = 6.426, P = 0.011) was also significant. Quantitative analysis using the family-based association test (FBAT) was significant for MOG4 in total Yale-Brown Obsessive-Compulsive Scale severity score (allele 2: z = 2.334, P = 0.020). Further investigations combining genetic, pathological, and pharmacological strategies, are warranted. PMID:15274043

  10. Genetic study of the myelin oligodendrocyte glycoprotein (MOG) gene in schizophrenia.

    PubMed

    Zai, G; King, N; Wigg, K; Couto, J; Wong, G W H; Honer, W G; Barr, C L; Kennedy, J L

    2005-02-01

    Schizophrenia (SCZ) is a neuropsychiatric disorder that affects approximately 1% of the general population. The human leukocyte antigen (HLA) system has been implicated in several genetic studies of SCZ. The myelin oligodendrocyte glycoprotein (MOG) gene, which is located close to the HLA region, is considered a candidate for SCZ due to its association with white matter abnormalities and its importance in mediating the complement cascade. Four polymorphisms in the MOG gene (CA)n (TAAA)n, and two intronic polymorphisms, C1334T and C10991T, were investigated for the possibility of association with SCZ using 111 SCZ proband and their families. We examined the transmission of the alleles of each of these polymorphisms with the transmission disequilibrium test. We did not observe significant evidence for biased transmission of alleles at the (CA)n (chi2=2.430, 6 df, P=0.876) (TAAA)n (chi2=3.550, 5 df, P=0.616), C1334T (chi2=0.040, 1 df, P=0.841) and C10991T (chi2=0.154, 1 df, P=0.695) polymorphisms. Overall haplotype analysis using the TRANSMIT program was also not significant (chi2=7.954, 9 df, P=0.539). Furthermore, our results comparing mean age at onset in the genotype groups using the Kruskal-Wallis Test were not significant. Our case-control analyses (182 cases age-, sex- and ethnicity-matched with healthy controls) and combined z-score [(CA)n: z-score=-1.126, P=0.130; (TAAA)n: z-score=-0.233, P=0.408; C1334T: z-score=0.703, P=0.241; C10991T: z-score=0.551, P=0.291] were also not significant. Although our data are negative, the intriguing hypothesis for MOG in SCZ may warrant further investigation of this gene. PMID:15660663

  11. Myelin oligodendrocyte glycoprotein antibodies are associated with a non-MS course in children

    PubMed Central

    Hacohen, Yael; Absoud, Michael; Deiva, Kumaran; Hemingway, Cheryl; Nytrova, Petra; Woodhall, Mark; Palace, Jacqueline; Wassmer, Evangeline; Tardieu, Marc; Vincent, Angela; Waters, Patrick

    2015-01-01

    Objective: To determine whether myelin oligodendrocyte glycoprotein antibodies (MOG-Abs) were predictive of a demyelination phenotype in children presenting with acquired demyelinating syndrome (ADS). Method: Sixty-five children with a first episode of ADS (12 acute disseminated encephalomyelitis, 24 optic neuritis, 18 transverse myelitis, 11 other clinically isolated syndrome) were identified from 2 national demyelination programs in the United Kingdom and France. Acute serum samples were tested for MOG-Abs by cell-based assay. Antibodies were used to predict diagnosis of multiple sclerosis (MS) at 1 year. Results: Twenty-three of 65 (35%) children had MOG-Abs. Antibody-positive and antibody-negative patients were not clinically different at presentation, but identification of MOG-Abs predicted a non-MS course at 1-year follow-up: only 2/23 (9%) MOG-Ab–positive patients were diagnosed with MS compared to 16/42 (38%) MOG-Ab–negative patients (p = 0.019, Fisher exact test). Antibody positivity at outset was a useful predictor for a non-MS disease course, with a positive predictive value of 91% (95% confidence interval [CI] 72–99), negative predictive value of 38% (95% CI 24–54), positive likelihood ratio of 4.02 (CI 1.0–15.4), and odds ratio of 6.5 (CI 1.3–31.3). Conclusions: MOG-Abs are found at presentation in 35% of patients with childhood ADS, across a range of demyelinating disorders. Antibody positivity can be useful in predicting a non-MS disease course at onset. PMID:25798445

  12. Infectious Mononucleosis Triggers Generation of IgG Auto-Antibodies against Native Myelin Oligodendrocyte Glycoprotein

    PubMed Central

    Kakalacheva, Kristina; Regenass, Stephan; Wiesmayr, Silke; Azzi, Tarik; Berger, Christoph; Dale, Russell C.; Brilot, Fabienne; Münz, Christian; Rostasy, Kevin; Nadal, David; Lünemann, Jan D.

    2016-01-01

    A history of infectious mononucleosis (IM), symptomatic primary infection with the Epstein Barr virus, is associated with the development of autoimmune diseases and increases the risk to develop multiple sclerosis. Here, we hypothesized that immune activation during IM triggers autoreactive immune responses. Antibody responses towards cellular antigens using a HEp-2 based indirect immunofluorescence assay and native myelin oligodendrocyte glycoprotein (MOG) using a flow cytometry-based assay were determined in 35 patients with IM and in 23 control subjects. We detected frequent immunoglobulin M (IgM) reactivity to vimentin, a major constituent of the intermediate filament family of proteins, in IM patients (27/35; 77%) but rarely in control subjects (2/23; 9%). IgG autoantibodies binding to HEp-2 cells were absent in both groups. In contrast, IgG responses to native MOG, present in up to 40% of children with inflammatory demyelinating diseases of the central nervous system (CNS), were detectable in 7/35 (20%) patients with IM but not in control subjects. Normalization of anti-vimentin IgM levels to increased total IgM concentrations during IM resulted in loss of significant differences for anti-vimentin IgM titers. Anti-MOG specific IgG responses were still detectable in a subset of three out of 35 patients with IM (9%), even after normalization to increased total IgG levels. Vimentin-specific IgM and MOG-specific IgG responses decreased following clinical resolution of acute IM symptoms. We conclude from our data that MOG-specific memory B cells are activated in subset of patients with IM. PMID:26907324

  13. Myelin-oligodendrocyte glycoprotein is a member of a subset of the immunoglobulin superfamily encoded within the major histocompatibility complex

    SciTech Connect

    Pham-Dinh, D.; Dautigny, A. ); Mattei, M.G.; Roeckel, N. ); Nussbaum, J.H.; Roussel, G. ); Pontarotti, P. ); Mather, I.H. ); Artzt, K. ); Lindahl, K.F. )

    1993-09-01

    Myelin/oligodendrocyte glycoprotein (MOG) is found on the surface of myelinating oligodendrocytes and external lamellae of myelin sheaths in the central nervous system, and it is target antigen in experimental autoimmune encephalomyelitis and multiple sclerosis. The authors have isolated bovine, mouse, and rat MOG cDNA clones and shown that the developmental pattern of MOG expression in the rat central nervous system coincides with the late stages of myelination. The amino-terminal, extracellular domain of MOG has characteristics of an immunoglobulin variable domain and is 46% and 41% identical with the amino terminus of bovine butyrophilin (expressed in the lactating mammary gland) and B-G antigens of the chicken major histocompatibility complex (MHC), respectively; these proteins thus form a subset of the immunoglobulin superfamily. The homology between MOG and B-G extends beyond their structure and genetic mapping to their ability to induce strong antibody responses and has implications for the role of MOG in pathological, autoimmune conditions. The authors colocalized the MOG and BT genes to the human MHC on chromosome 6p21.3-p22. The mouse MOG gene was mapped to the homologous band C of chromosome 17, within the M region of the mouse MHC. 38 refs., 6 figs.

  14. Myelin/oligodendrocyte glycoprotein is a member of a subset of the immunoglobulin superfamily encoded within the major histocompatibility complex.

    PubMed

    Pham-Dinh, D; Mattei, M G; Nussbaum, J L; Roussel, G; Pontarotti, P; Roeckel, N; Mather, I H; Artzt, K; Lindahl, K F; Dautigny, A

    1993-09-01

    Myelin/oligodendrocyte glycoprotein (MOG) is found on the surface of myelinating oligodendrocytes and external lamellae of myelin sheaths in the central nervous system, and it is a target antigen in experimental autoimmune encephalomyelitis and multiple sclerosis. We have isolated bovine, mouse, and rat MOG cDNA clones and shown that the developmental pattern of MOG expression in the rat central nervous system coincides with the late stages of myelination. The amino-terminal, extracellular domain of MOG has characteristics of an immunoglobulin variable domain and is 46% and 41% identical with the amino terminus of bovine butyrophilin (expressed in the lactating mammary gland) and B-G antigens of the chicken major histocompatibility complex (MHC), respectively; these proteins thus form a subset of the immunoglobulin superfamily. The homology between MOG and B-G extends beyond their structure and genetic mapping to their ability to induce strong antibody responses and has implications for the role of MOG in pathological, autoimmune conditions. We colocalized the MOG and BT genes to the human MHC on chromosome 6p21.3-p22. The mouse MOG gene was mapped to the homologous band C of chromosome 17, within the M region of the mouse MHC. PMID:8367453

  15. Molecular dynamics at the receptor level of immunodominant myelin oligodendrocyte glycoprotein 35-55 epitope implicated in multiple sclerosis.

    PubMed

    Yannakakis, Mary Patricia; Tzoupis, Haralambos; Michailidou, Elena; Mantzourani, Efthimia; Simal, Carmen; Tselios, Theodore

    2016-07-01

    Multiple Sclerosis (MS) is a common autoimmune disease whereby myelin is destroyed by the immune system. The disease is triggered by the stimulation of encephalitogenic T-cells via the formation of a trimolecular complex between the Human Leukocyte Antigen (HLA), an immunodominant epitope of myelin proteins and T-cell Receptor (TCR). Myelin Oligodendrocyte Glycoprotein (MOG) is located on the external surface of myelin and has been implicated in MS induction. The immunodominant 35-55 epitope of MOG is widely used for in vivo biological evaluation and immunological studies that are related with chronic Experimental Autoimmune Encephalomyelitis (EAE, animal model of MS), inflammatory diseases and MS. In this report, Molecular Dynamics (MD) simulations were used to explore the interactions of MOG35-55 at the receptor level. A detailed mapping of the developed interactions during the creation of the trimolecular complex is reported. This is the first attempt to gain an understanding of the molecular recognition of the MOG35-55 epitope by the HLA and TCR receptors. During the formation of the trimolecular complex, the residues Arg(41) and Arg(46) of MOG35-55 have been confirmed to serve as TCR anchors while Tyr(40) interacts with HLA. The present structural findings indicate that the Arg at positions 41 and 46 is a key residue for the stimulation of the encephalitogenic T-cells. PMID:27388119

  16. Changes in different parameters, lymphocyte proliferation and hematopoietic progenitor colony formation in EAE mice treated with myelin oligodendrocyte glycoprotein.

    PubMed

    Doronin, Vasilii B; Parkhomenko, Taisiya A; Korablev, Alexey; Toporkova, Ludmila B; Lopatnikova, Julia A; Alshevskaja, Alina A; Sennikov, Sergei V; Buneva, Valentina N; Budde, Thomas; Meuth, Sven G; Orlovskaya, Irina A; Popova, Nelly A; Nevinsky, Georgy A

    2016-01-01

    Myelin oligodendrocyte glycoprotein (MOG) is an antigen of the myelin sheath, which may trigger immune cell responses and the production of auto-antibodies in multiple sclerosis (MS). In this study, we used MOG(35-55) -induced experimental autoimmune encephalomyelitis (EAE), a model of human MS, to assess the production of catalytically active immunoglobulin G (IgG) antibodies or abzymes which have been shown to be present in sera of patients with several autoimmune diseases. Here, we show that IgGs from the sera of control C57BL/6 mice are catalytically inactive. During development of EAE, a specific reorganization of the immune system of mice occurred leading to a condition which was associated with the generation of catalytically active IgGs hydrolysing DNA, myelin basic protein (MBP) and MOG which was associated with increased proteinuria, changes in differentiation of mice bone marrow hematopoietic stem cells (HSCs) and an increase in proliferation of lymphocytes in bone marrow, spleen and thymus as well as a significant suppression of cell apoptosis in these organs. The strongest alterations were found in the early disease phase (18-24 days after immunization) and were less pronounced in later EAE stages (40 days after EAE induction). We conclude that a significant increase in DNase and proteolytic activities of antibodies may be considered the earliest statistically significant marker of MOG-induced EAE in mice. The possible differences in immune system reorganizations during preclinical phases of the disease, acute and late EAE, leading to production of different auto-antibodies and abzymes as well other changes are discussed. PMID:26493273

  17. Linkage disequilibrium analysis of polymorphisms in the gene for myelin oligodendrocyte glycoprotein in Tourette's syndrome patients from a Chinese sample.

    PubMed

    Huang, Yi; Li, Tao; Wang, Yun; Ansar, Jawaid; Lanting, Guo; Liu, Xiehe; Zhao, Jing Hua; Hu, Xun; Sham, Pak C; Collier, David

    2004-01-01

    Gilles de la Tourette syndrome (GTS) is a neuropsychiatric disorder characterised by multiple motor and phonic tics, which wax and wane. Recently, evidence has accumulated supporting the role of autoimmune mechanisms in the aetiology of GTS, suggesting that it is within the paediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS) spectrum of childhood neurobehavioural disorders. An immunopathogenic role of antibodies against myelin oligodendrocyte glycoprotein (MOG) has been suggested in this syndrome. In this study, we investigate the association of three microsatellite polymorphisms (MOGa, MOGb, MOGc) in the gene for MOG with GTS in 197 family trios collected from southwest China. Linkage disequilibrium between these three markers was observed with the strongest between MOGa and MOGc (D' = 0.541, P = 0.000). We did not find overall significant evidence for distorted transmission of any of these three markers of MOG gene in GTS, although we observed a weak preferential transmission of the 148 bp allele of MOGc (chi(2) = 4.000, P = 0.046) which did not survive correction for multiple testing. Our results suggest that there is no association between the MOG gene polymorphisms we tested and GTS. PMID:14681920

  18. Myelin Oligodendrocyte Glycoprotein-Associated Pediatric Central Nervous System Demyelination: Clinical Course, Neuroimaging Findings, and Response to Therapy.

    PubMed

    Thulasirajah, Salini; Pohl, Daniela; Davila-Acosta, Jorge; Venkateswaran, Sunita

    2016-08-01

    Under the umbrella of pediatric-acquired demyelinating syndromes, there is a multitude of disorders, including optic neuritis, transverse myelitis, acute disseminated encephalomyelitis (ADEM), multiple sclerosis (MS), and neuromyelitis optica spectrum disorders (NMOSD). Due to overlapping clinical and magnetic resonance imaging (MRI) features, it can be challenging to provide an accurate diagnosis. In view of therapeutic and prognostic implications, an early and reliable diagnosis is however of utmost importance. Recent studies of myelin oligodendrocyte glycoprotein (MOG) identify MOG, as a promising target for antibody-mediated demyelination and a biomarker for a relatively benign and non-MS disease course. We describe the clinical and MRI presentation of five children presenting with an acute, severe central nervous system inflammatory disease involving the brain and spinal cord, all of whom were positive for MOG-IgG antibody. Encephalopathy was uncommon at presentation and all had quick resolution of symptoms with intravenous steroid and intravenous immunoglobulin (IVIG) treatment. All patients recovered well, and have been treated with IVIG to potentially prevent relapses. PMID:27128728

  19. The Extracellular Domain of Myelin Oligodendrocyte Glycoprotein Elicits Atypical Experimental Autoimmune Encephalomyelitis in Rat and Macaque Species

    PubMed Central

    Curtis, Alan D.; Taslim, Najla; Reece, Shaun P.; Grebenciucova, Elena; Ray, Richard H.; Rosenbaum, Matthew D.; Wardle, Robert L.; Van Scott, Michael R.; Mannie, Mark D.

    2014-01-01

    Atypical models of experimental autoimmune encephalomyelitis (EAE) are advantageous in that the heterogeneity of clinical signs appears more reflective of those in multiple sclerosis (MS). Conversely, models of classical EAE feature stereotypic progression of an ascending flaccid paralysis that is not a characteristic of MS. The study of atypical EAE however has been limited due to the relative lack of suitable models that feature reliable disease incidence and severity, excepting mice deficient in gamma-interferon signaling pathways. In this study, atypical EAE was induced in Lewis rats, and a related approach was effective for induction of an unusual neurologic syndrome in a cynomolgus macaque. Lewis rats were immunized with the rat immunoglobulin variable (IgV)-related extracellular domain of myelin oligodendrocyte glycoprotein (IgV-MOG) in complete Freund’s adjuvant (CFA) followed by one or more injections of rat IgV-MOG in incomplete Freund’s adjuvant (IFA). The resulting disease was marked by torticollis, unilateral rigid paralysis, forelimb weakness, and high titers of anti-MOG antibody against conformational epitopes of MOG, as well as other signs of atypical EAE. A similar strategy elicited a distinct atypical form of EAE in a cynomolgus macaque. By day 36 in the monkey, titers of IgG against conformational epitopes of extracellular MOG were evident, and on day 201, the macaque had an abrupt onset of an unusual form of EAE that included a pronounced arousal-dependent, transient myotonia. The disease persisted for 6–7 weeks and was marked by a gradual, consistent improvement and an eventual full recovery without recurrence. These data indicate that one or more boosters of IgV-MOG in IFA represent a key variable for induction of atypical or unusual forms of EAE in rat and Macaca species. These studies also reveal a close correlation between humoral immunity against conformational epitopes of MOG, extended confluent demyelinating plaques in spinal cord

  20. Myelin oligodendrocyte glycoprotein induces incomplete tolerance of CD4(+) T cells specific for both a myelin and a neuronal self-antigen in mice.

    PubMed

    Lucca, Liliana E; Axisa, Pierre-Paul; Aloulou, Meryem; Perals, Corine; Ramadan, Abdulraouf; Rufas, Pierre; Kyewski, Bruno; Derbinski, Jens; Fazilleau, Nicolas; Mars, Lennart T; Liblau, Roland S

    2016-09-01

    T-cell polyspecificity, predicting that individual T cells recognize a continuum of related ligands, implies that multiple antigens can tolerize T cells specific for a given self-antigen. We previously showed in C57BL/6 mice that part of the CD4(+) T-cell repertoire specific for myelin oligodendrocyte glycoprotein (MOG) 35-55 also recognizes the neuronal antigen neurofilament medium (NF-M) 15-35. Such bi-specific CD4(+) T cells are frequent and produce inflammatory cytokines after stimulation. Since T cells recognizing two self-antigens would be expected to be tolerized more efficiently, this finding prompted us to study how polyspecificity impacts tolerance. We found that similar to MOG, NF-M is expressed in the thymus by medullary thymic epithelial cells, a tolerogenic population. Nevertheless, the frequency, phenotype, and capacity to transfer experimental autoimmune encephalomyelitis (EAE) of MOG35-55 -reactive CD4(+) T cells were increased in MOG-deficient but not in NF-M-deficient mice. We found that presentation of NF-M15-35 by I-A(b) on dendritic cells is of short duration, suggesting unstable MHC class II binding. Consistently, introducing an MHC-anchoring residue into NF-M15-35 (NF-M15-35 T20Y) increased its immunogenicity, activating a repertoire able to induce EAE. Our results show that in C57BL/6 mice bi-specific encephalitogenic T cells manage to escape tolerization due to inefficient exposure to two self-antigens. PMID:27334749

  1. Increased interleukin-6 correlates with myelin oligodendrocyte glycoprotein antibodies in pediatric monophasic demyelinating diseases and multiple sclerosis.

    PubMed

    Horellou, Philippe; Wang, Min; Keo, Vixra; Chrétien, Pascale; Serguera, Ché; Waters, Patrick; Deiva, Kumaran

    2015-12-15

    Acquired demyelinating syndromes (ADS) in children evolve either as a monophasic disease diagnosed as acute demyelinating encephalomyelitis (ADEM), transverse myelitis (TM) or optic neuritis (ON), or a multiphasic one with several relapses most often leading to the diagnosis of multiple sclerosis (MS) or neuromyelitis optica (NMO). These neuroinflammatory disorders are increasingly associated with autoantibodies against proteins such as aquaporin-4 in rare instances, and more frequently against myelin oligodendrocyte glycoprotein (MOG). Recently, in adult NMO patients, C5a levels were shown to be elevated in cerebrospinal fluid (CSF) during acute exacerbation. We investigated the CSF levels of anaphylatoxins and pro-inflammatory cytokines, and plasma MOG antibodies in onset samples from children with ADS. Thirty four children presenting with a first episode of ADS, 17 with monophasic ADS (9 with ADEM, 4 with TM and 4 with ON) and 17 with MS, who had paired blood and CSF samples at onset were included and compared to 12 patients with other non-inflammatory neurological disorders (OND). Cytokines and anaphylatoxins in CSF were measured by Cytometric Bead Array immunoassay. MOG antibody titers in plasma were tested by flow cytometry using a stable cell line expressing full-length human MOG. We found a significant increase in C5a levels in the CSF of patients with monophasic ADS (n=17) compared to OND (n=12, p=0.0036) and to MS (n=17, p=0.0371). The C5a levels in MS were higher than in OND without reaching significance (p=0.2). CSF IL-6 levels were significantly increased in monophasic ADS compared to OND (p=0.0027) and to MS (p=0.0046). MOG antibody plasma levels were significantly higher in monophasic ADS (p<0.0001) and, to a lesser extent, in MS compared to OND (p=0.0023). Plasma MOG antibodies and CSF IL-6 levels were significantly correlated (r=0.51, p=0.018). CSF C5a and IL-6 levels are increased in monophasic ADS but not in MS when compared to OND, suggesting

  2. Immune modulation by a tolerogenic myelin oligodendrocyte glycoprotein (MOG)10–60 containing fusion protein in the marmoset experimental autoimmune encephalomyelitis model

    PubMed Central

    Kap, Y S; van Driel, N; Arends, R; Rouwendal, G; Verolin, M; Blezer, E; Lycke, N; ‘t Hart, B A

    2015-01-01

    Current therapies for multiple sclerosis (MS), a chronic autoimmune neuroinflammatory disease, mostly target general cell populations or immune molecules, which may lead to a compromised immune system. A more directed strategy would be to re-enforce tolerance of the autoaggressive T cells that drive tissue inflammation and injury. In this study, we have investigated whether the course of experimental autoimmune encephalomyelitis (EAE) in mice and marmosets can be altered by a potent tolerizing fusion protein. In addition, a multi-parameter immunological analysis was performed in marmosets to assess whether the treatment induces modulation of EAE-associated cellular and humoral immune reactions. The fusion protein, CTA1R9K-hMOG10–60-DD, contains a mutated cholera toxin A1 subunit (CTA1R9K), a dimer of the Ig binding D region of Staphylococcus aureus protein A (DD), and the human myelin oligodendrocyte glycoprotein (hMOG) sequence 10–60. We observed that intranasal application of CTA1R9K-hMOG10–60-DD seems to skew the immune response against myelin oligodendrocyte glycoprotein (MOG) towards a regulatory function. We show a reduced number of circulating macrophages, reduced MOG-induced expansion of mononuclear cells in peripheral blood, reduced MOG-induced production of interleukin (IL)-17A in spleen, increased MOG-induced production of IL-4 and IL-10 and an increased percentage of cells expressing programmed cell death-1 (PD-1) and CC chemokine receptor 4 (CCR4). Nevertheless, the treatment did not detectably change the EAE course and pathology. Thus, despite a detectable effect on relevant immune parameters, the fusion protein failed to influence the clinical and pathological outcome of disease. This result warrants further development and improvement of this specifically targeted tolerance inducing therapy. PMID:25393803

  3. Marmoset fine B cell and T cell epitope specificities mapped onto a homology model of the extracellular domain of human myelin oligodendrocyte glycoprotein.

    PubMed

    Mesleh, Michael F; Belmar, Nicole; Lu, Chuan Wei; Krishnan, V V; Maxwell, Robert S; Genain, Claude P; Cosman, Monique

    2002-03-01

    Aberrant association of autoantibodies with myelin oligodendrocyte glycoprotein (MOG), an integral membrane protein of the central nervous system (CNS) myelin, has been implicated in the pathogenesis of multiple sclerosis (MS). Sensitization of nonhuman primates (Callithrix jacchus marmosets) against the nonglycosylated, recombinant N-terminal domain of rat MOG (residues 1-125) reproduces an MS-like disease in which MOG-specific autoantibodies directly mediate demyelination. To assess the interrelationship between MOG structure and the induction of autoimmune CNS diseases and to enable structure-based rational design of therapeutics, a homology model of human MOG(2-120) was constructed based on consensus residues found in immunoglobulin superfamily variable-type proteins having known structures. Possible sites for posttranslational modifications and dimerization have also been identified and analyzed. The B cell and T cell epitopes have been identified in rat MOG-immunized marmosets, and these sequences are observed to map primarily onto accessible regions in the model, which may explain their ability to generate potent antibody responses. PMID:11895369

  4. Rational design and synthesis of altered peptide ligands based on human myelin oligodendrocyte glycoprotein 35-55 epitope: inhibition of chronic experimental autoimmune encephalomyelitis in mice.

    PubMed

    Tselios, Theodore; Aggelidakis, Mihalis; Tapeinou, Anthi; Tseveleki, Vivian; Kanistras, Ioannis; Gatos, Dimitrios; Matsoukas, John

    2014-01-01

    Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease of the central nervous system and is an animal model of multiple sclerosis (MS). Although the etiology of MS remains unclear, there is evidence T-cell recognition of immunodominant epitopes of myelin proteins, such as the 35-55 epitope of myelin oligodendrocyte glycoprotein (MOG), plays a pathogenic role in the induction of chronic EAE. Cyclization of peptides is of great interest since the limited stability of linear peptides restricts their potential use as therapeutic agents. Herein, we have designed and synthesized a number of linear and cyclic peptides by mutating crucial T cell receptor (TCR) contact residues of the human MOG35-55 epitope. In particular, we have designed and synthesized cyclic altered peptide ligands (APLs) by mutating Arg41 with Ala or Arg41 and Arg46 with Ala. The peptides were synthesized in solid phase on 2-chlorotrityl chloride resin (CLTR-Cl) using the Fmoc/t-Bu methodology. The purity of final products was verified by RP-HPLC and their identification was achieved by ESI-MS. It was found that the substitutions of Arg at positions 41 and 46 with Ala results in peptide analogues that reduce the severity of MOG-induced EAE clinical symptoms in C57BL/6 mice when co-administered with mouse MOG35-55 peptide at the time of immunization. PMID:25375337

  5. Lymphocryptovirus Infection of Nonhuman Primate B Cells Converts Destructive into Productive Processing of the Pathogenic CD8 T Cell Epitope in Myelin Oligodendrocyte Glycoprotein

    PubMed Central

    Jagessar, S. Anwar; Holtman, Inge R.; Hofman, Sam; Morandi, Elena; Heijmans, Nicole; Laman, Jon D.; Gran, Bruno; Faber, Bart W.; van Kasteren, Sander I.; Eggen, Bart J. L.

    2016-01-01

    EBV is the major infectious environmental risk factor for multiple sclerosis (MS), but the underlying mechanisms remain obscure. Patient studies do not allow manipulation in vivo. We used the experimental autoimmune encephalomyelitis (EAE) models in the common marmoset and rhesus monkey to model the association of EBV and MS. We report that B cells infected with EBV-related lymphocryptovirus (LCV) are requisite APCs for MHC-E–restricted autoaggressive effector memory CTLs specific for the immunodominant epitope 40-48 of myelin oligodendrocyte glycoprotein (MOG). These T cells drive the EAE pathogenesis to irreversible neurologic deficit. The aim of this study was to determine why LCV infection is important for this pathogenic role of B cells. Transcriptome comparison of LCV-infected B cells and CD20+ spleen cells from rhesus monkeys shows increased expression of genes encoding elements of the Ag cross-presentation machinery (i.e., of proteasome maturation protein and immunoproteasome subunits) and enhanced expression of MHC-E and of costimulatory molecules (CD70 and CD80, but not CD86). It was also shown that altered expression of endolysosomal proteases (cathepsins) mitigates the fast endolysosomal degradation of the MOG40–48 core epitope. Finally, LCV infection also induced expression of LC3-II+ cytosolic structures resembling autophagosomes, which seem to form an intracellular compartment where the MOG40–48 epitope is protected against proteolytic degradation by the endolysosomal serine protease cathepsin G. In conclusion, LCV infection induces a variety of changes in B cells that underlies the conversion of destructive processing of the immunodominant MOG40–48 epitope into productive processing and cross-presentation to strongly autoaggressive CTLs. PMID:27412414

  6. Lymphocryptovirus Infection of Nonhuman Primate B Cells Converts Destructive into Productive Processing of the Pathogenic CD8 T Cell Epitope in Myelin Oligodendrocyte Glycoprotein.

    PubMed

    Jagessar, S Anwar; Holtman, Inge R; Hofman, Sam; Morandi, Elena; Heijmans, Nicole; Laman, Jon D; Gran, Bruno; Faber, Bart W; van Kasteren, Sander I; Eggen, Bart J L; 't Hart, Bert A

    2016-08-15

    EBV is the major infectious environmental risk factor for multiple sclerosis (MS), but the underlying mechanisms remain obscure. Patient studies do not allow manipulation in vivo. We used the experimental autoimmune encephalomyelitis (EAE) models in the common marmoset and rhesus monkey to model the association of EBV and MS. We report that B cells infected with EBV-related lymphocryptovirus (LCV) are requisite APCs for MHC-E-restricted autoaggressive effector memory CTLs specific for the immunodominant epitope 40-48 of myelin oligodendrocyte glycoprotein (MOG). These T cells drive the EAE pathogenesis to irreversible neurologic deficit. The aim of this study was to determine why LCV infection is important for this pathogenic role of B cells. Transcriptome comparison of LCV-infected B cells and CD20(+) spleen cells from rhesus monkeys shows increased expression of genes encoding elements of the Ag cross-presentation machinery (i.e., of proteasome maturation protein and immunoproteasome subunits) and enhanced expression of MHC-E and of costimulatory molecules (CD70 and CD80, but not CD86). It was also shown that altered expression of endolysosomal proteases (cathepsins) mitigates the fast endolysosomal degradation of the MOG40-48 core epitope. Finally, LCV infection also induced expression of LC3-II(+) cytosolic structures resembling autophagosomes, which seem to form an intracellular compartment where the MOG40-48 epitope is protected against proteolytic degradation by the endolysosomal serine protease cathepsin G. In conclusion, LCV infection induces a variety of changes in B cells that underlies the conversion of destructive processing of the immunodominant MOG40-48 epitope into productive processing and cross-presentation to strongly autoaggressive CTLs. PMID:27412414

  7. Epitope mapping of anti-myelin oligodendrocyte glycoprotein (MOG) antibodies in a mouse model of multiple sclerosis: microwave-assisted synthesis of the peptide antigens and ELISA screening.

    PubMed

    Pacini, Giulia; Ieronymaki, Matthaia; Nuti, Francesca; Sabatino, Giuseppina; Larregola, Maud; Aharoni, Rina; Papini, Anna Maria; Rovero, Paolo

    2016-01-01

    The role of pathologic auto-antibodies against myelin oligodendrocyte glycoprotein (MOG) in multiple sclerosis is a highly controversial matter. As the use of animal models may enable to unravel the molecular mechanisms of the human disorder, numerous studies on multiple sclerosis are carried out using experimental autoimmune encephalomyelitis (EAE). In particular, the most extensively used EAE model is obtained by immunizing C57BL/6 mice with the immunodominant peptide MOG(35-55). In this scenario, we analyzed the anti-MOG antibody response in this model using the recombinant refolded extracellular domain of the protein, MOG(1-117). To assess the presence of a B-cell intramolecular epitope spreading mechanism, we tested also five synthetic peptides mapping the 1-117 sequence of MOG, including MOG(35-55). For this purpose, we cloned, expressed in Escherichia coli and on-column refolded MOG(1-117), and we applied an optimized microwave-assisted solid-phase synthetic strategy to obtain the designed peptide sequences. Subsequently, we set up a solid-phase immunoenzymatic assay testing both naïve and EAE mice sera and using MOG protein and peptides as antigenic probes. The results obtained disclose an intense IgG antibody response against both the recombinant protein and the immunizing peptide, while no response was observed against the other synthetic fragments, thus excluding the presence of an intramolecular epitope spreading mechanism. Furthermore, as the properly refolded recombinant probe is able to bind antibodies with greater efficiency compared with MOG(35-55), we hypothesize the presence of both linear and conformational epitopes on MOG(35-55) sequence. PMID:26663200

  8. Myelin oligodendrocyte glycoprotein (MOG35-55)-induced experimental autoimmune encephalomyelitis is ameliorated in interleukin-32 alpha transgenic mice.

    PubMed

    Yun, Jaesuk; Gu, Sun Mi; Yun, Hyung Mun; Son, Dong Ju; Park, Mi Hee; Lee, Moon Soon; Hong, Jin Tae

    2015-12-01

    Multiple sclerosis (MS), also known as disseminated sclerosis or encephalomyelitis disseminate, is an inflammatory disease in which myelin in the spinal cord and brain are damaged. IL-32α is known as a critical molecule in the pathophysiology of immune-mediated chronic inflammatory disease such as rheumatoid arthritis, chronic pulmonary disease, and cancers. However, the role of IL-32α on spinal cord injuries and demyelination is poorly understood. Recently, we reported that the release of proinflammatory cytokines were reduced in IL-32α-overexpressing transgenic mice. In this study, we investigated whether IL-32α plays a role on MS using experimental autoimmune encephalomyelitis (EAE), an experimental mouse model of MS, in human IL-32α Tg mice. The Tg mice were immunized with MOG35-55 suspended in CFA emulsion followed by pertussis toxin, and then EAE paralysis of mice was scored. We observed that the paralytic severity and neuropathology of EAE in IL-32α Tg mice were significantly decreased compared with that of non-Tg mice. The immune cells infiltration, astrocytes/microglials activation, and pro-inflammatory cytokines (IL-1β and IL-6) levels in spinal cord were suppressed in IL-32α Tg mice. Furthermore, NG2 and O4 were decreased in IL-32α Tg mice, indicating that spinal cord damaging was suppressed. In addition, in vitro assay also revealed that IL-32α has a preventive role against Con A stimulation which is evidenced by decrease in T cell proliferation and inflammatory cytokine levels in IL-32α overexpressed Jurkat cell. Taken together, our findings suggested that IL-32α may play a protective role in EAE by suppressing neuroinflammation in spinal cord. PMID:26564962

  9. An Adult Case of Anti-Myelin Oligodendrocyte Glycoprotein (MOG) Antibody-associated Multiphasic Acute Disseminated Encephalomyelitis at 33-year Intervals.

    PubMed

    Numa, Soichiro; Kasai, Takashi; Kondo, Takayuki; Kushimura, Yukie; Kimura, Ayaka; Takahashi, Hisashi; Morita, Kanako; Tanaka, Akihiro; Noto, Yu-Ichi; Ohara, Tomoyuki; Nakagawa, Masanori; Mizuno, Toshiki

    2016-01-01

    Acute disseminated encephalomyelitis (ADEM) followed by optic neuritis (ON) has been reported as a distinct phenotype associated with anti-myelin oligodendrocyte protein (MOG) antibody. We herein report the case of a 37-year-old woman who was diagnosed with ADEM at 4 years old of age and who subsequently developed ON followed by recurrent ADEM 33 years after the initial onset. A serum analysis showed anti-MOG antibody positivity. This phenotype has only previously been reported in pediatric cases. Neurologists thus need to be aware that the phenotype may occur in adult patients, in whom it may be assumed to be atypical multiple sclerosis. PMID:26984094

  10. Antibodies to Aquaporin 4, Myelin-Oligodendrocyte Glycoprotein, and the Glycine Receptor α1 Subunit in Patients With Isolated Optic Neuritis

    PubMed Central

    Martinez-Hernandez, Eugenia; Sepulveda, Maria; Rostásy, Kevin; Höftberger, Romana; Graus, Francesc; Harvey, Robert J.; Saiz, Albert; Dalmau, Josep

    2016-01-01

    IMPORTANCE In patients with isolated optic neuritis (ON), the presence of antibodies to aquaporin 4 (AQP4) has diagnostic and prognostic value. In the same clinical setting, the significance of antibodies to myelin-oligodendrocyte glycoprotein (MOG) or the glycine receptor α1 subunit (GlyR) is unclear. OBJECTIVES To investigate the frequency of antibodies to AQP4, MOG, and GlyR in patients with unilateral or bilateral, severe, or recurrent isolated ON and to determine their clinical and prognostic correlates. DESIGN, SETTING, AND PARTICIPANTS Retrospective case-control study from November 1, 2005, through May 30, 2014 with the detection of autoantibodies in a neuroimmunology referral center. We included 51 patients with ON but without clinical and magnetic resonance imaging findings outside the optic nerves and 142 controls (30 healthy individuals, 48 patients with neuromyelitis optica, and 64 patients with multiple sclerosis). MAIN OUTCOMES AND MEASURES Clinicoimmunologic analysis. We determined the presence of antibodies to AQP4, MOG, and GlyR using cell-based assays. RESULTS The median age of the patients at the onset of ON symptoms was 28 (range, 5–65) years; 36 patients (71%) were female. Antibodies were identified in 23 patients (45%), including MOG in 10 patients, AQP4 in 6 patients, and GlyR in 7 patients (concurrent with MOG in 3 and concurrent with AQP4 in 1). Patients with AQP4 antibodies (median visual score, 3.5 [range, 1–9]) had a worse visual outcome than patients with MOG antibodies alone (median visual score, 0 [range, 0–5]; P = .007), patients with seronegative findings (n = 28) (median visual score, 1.0 [range, 0–14]; P = .08), and patients with GlyR antibodies alone (n = 3) (median visual score, 0 [range, 0–2]; P = .10). The median age of the 7 patients with GlyR antibodies was 27 (range, 11–38) years; 5 (71%) of these were female. Among the 3 patients with GlyR antibodies alone, 1 patient had monophasic ON, 1 had recurrent isolated

  11. Linking oligodendrocyte and myelin dysfunction to neurocircuitry abnormalities in schizophrenia

    PubMed Central

    Takahashi, Nagahide; Sakurai, Takeshi; Davis, Kenneth L.; Buxbaum, Joseph D.

    2010-01-01

    Multiple lines of evidence in schizophrenia, from brain imaging, studies in postmortem brains, and genetic association studies, have implicated oligodendrocyte and myelin dysfunction in this disease. Recent studies suggest that oligodendrocyte and myelin dysfunction leads to changes in synaptic formation and function, which could lead to cognitive dysfunction, a core symptom of schizophrenia. Furthermore, there is accumulating data linking oligodendrocyte and myelin dysfunction with dopamine and glutamate abnormalities, both of which are found in schizophrenia. These findings implicate oligodendrocyte and myelin dysfunction as a primary change in schizophrenia, not only as secondary consequences of the illness or treatment. Strategies targeting oligodendrocyte and myelin abnormalities could therefore provide therapeutic opportunities for patients suffering from schizophrenia. PMID:20950668

  12. CNS Myelin Sheath Lengths Are an Intrinsic Property of Oligodendrocytes

    PubMed Central

    Bechler, Marie E.; Byrne, Lauren; ffrench-Constant, Charles

    2015-01-01

    Summary Since Río-Hortega’s description of oligodendrocyte morphologies nearly a century ago, many studies have observed myelin sheath-length diversity between CNS regions [1–3]. Myelin sheath length directly impacts axonal conduction velocity by influencing the spacing between nodes of Ranvier. Such differences likely affect neural signal coordination and synchronization [4]. What accounts for regional differences in myelin sheath lengths is unknown; are myelin sheath lengths determined solely by axons or do intrinsic properties of different oligodendrocyte precursor cell populations affect length? The prevailing view is that axons provide molecular cues necessary for oligodendrocyte myelination and appropriate sheath lengths. This view is based upon the observation that axon diameters correlate with myelin sheath length [1, 5, 6], as well as reports that PNS axonal neuregulin-1 type III regulates the initiation and properties of Schwann cell myelin sheaths [7, 8]. However, in the CNS, no such instructive molecules have been shown to be required, and increasing in vitro evidence supports an oligodendrocyte-driven, neuron-independent ability to differentiate and form initial sheaths [9–12]. We test this alternative signal-independent hypothesis—that variation in internode lengths reflects regional oligodendrocyte-intrinsic properties. Using microfibers, we find that oligodendrocytes have a remarkable ability to self-regulate the formation of compact, multilamellar myelin and generate sheaths of physiological length. Our results show that oligodendrocytes respond to fiber diameters and that spinal cord oligodendrocytes generate longer sheaths than cortical oligodendrocytes on fibers, co-cultures, and explants, revealing that oligodendrocytes have regional identity and generate different sheath lengths that mirror internodes in vivo. PMID:26320951

  13. CNS myelin sheath is stochastically built by homotypic fusion of myelin membranes within the bounds of an oligodendrocyte process.

    PubMed

    Szuchet, Sara; Nielsen, Lauren L; Domowicz, Miriam S; Austin, Jotham R; Arvanitis, Dimitrios L

    2015-04-01

    Myelin - the multilayer membrane that envelops axons - is a facilitator of rapid nerve conduction. Oligodendrocytes form CNS myelin; the prevailing hypothesis being that they do it by extending a process that circumnavigates the axon. It is pertinent to ask how myelin is built because oligodendrocyte plasma membrane and myelin are compositionally different. To this end, we examined oligodendrocyte cultures and embryonic avian optic nerves by electron microscopy, immuno-electron microscopy and three-dimensional electron tomography. The results support three novel concepts. Myelin membranes are synthesized as tubules and packaged into "myelinophore organelles" in the oligodendrocyte perikaryon. Myelin membranes are matured in and transported by myelinophore organelles within an oligodendrocyte process. The myelin sheath is generated by myelin membrane fusion inside an oligodendrocyte process. These findings abrogate the dogma of myelin resulting from a wrapping motion of an oligodendrocyte process and open up new avenues in the quest for understanding myelination in health and disease. PMID:25682762

  14. CaMKIIβ regulates oligodendrocyte maturation and CNS myelination.

    PubMed

    Waggener, Christopher T; Dupree, Jeffrey L; Elgersma, Ype; Fuss, Babette

    2013-06-19

    CNS myelination and the maturation of the myelinating cells of the CNS, namely oligodendrocytes, are thought to be regulated by molecular mechanisms controlling the actin cytoskeleton. However, the exact nature of these mechanisms is currently only poorly understood. Here we assessed the role of calcium/calmodulin-dependent kinase type II (CaMKII), in particular CaMKIIβ, in oligodendrocyte maturation and CNS myelination. Using in vitro culture studies, our data demonstrate that CaMKIIβ is critical for the proper morphological maturation of differentiating oligodendrocytes, an aspect of oligodendrocyte maturation that is mediated to a large extent by changes in the cellular cytoskeleton. Furthermore, our data provide evidence for an actin-cytoskeleton-stabilizing role of CaMKIIβ in differentiating oligodendrocytes. Using Camk2b knock-out and Camk2b(A303R) mutant mice, our data revealed an in vivo functional role of CaMKIIβ in regulating myelin thickness that may be mediated by a non-kinase-catalytic activity. Our data point toward a critical role of CaMKIIβ in regulating oligodendrocyte maturation and CNS myelination via an actin-cytoskeleton-regulatory mechanism. PMID:23785157

  15. Myocilin is involved in NgR1/Lingo-1-mediated oligodendrocyte differentiation and myelination of the optic nerve.

    PubMed

    Kwon, Heung Sun; Nakaya, Naoki; Abu-Asab, Mones; Kim, Hong Sug; Tomarev, Stanislav I

    2014-04-16

    Myocilin is a secreted glycoprotein that belongs to a family of olfactomedin domain-containing proteins. Although myocilin is detected in several ocular and nonocular tissues, the only reported human pathology related to mutations in the MYOCILIN gene is primary open-angle glaucoma. Functions of myocilin are poorly understood. Here we demonstrate that myocilin is a mediator of oligodendrocyte differentiation and is involved in the myelination of the optic nerve in mice. Myocilin is expressed and secreted by optic nerve astrocytes. Differentiation of optic nerve oligodendrocytes is delayed in Myocilin-null mice. Optic nerves of Myocilin-null mice contain reduced levels of several myelin-associated proteins including myelin basic protein, myelin proteolipid protein, and 2'3'-cyclic nucleotide 3'-phosphodiesterase compared with those of wild-type littermates. This leads to reduced myelin sheath thickness of optic nerve axons in Myocilin-null mice compared with wild-type littermates, and this difference is more pronounced at early postnatal stages compared with adult mice. Myocilin also affects differentiation of oligodendrocyte precursors in vitro. Its addition to primary cultures of differentiating oligodendrocyte precursors increases levels of tested markers of oligodendrocyte differentiation and stimulates elongation of oligodendrocyte processes. Myocilin stimulation of oligodendrocyte differentiation occurs through the NgR1/Lingo-1 receptor complex. Myocilin physically interacts with Lingo-1 and may be considered as a Lingo-1 ligand. Myocilin-induced elongation of oligodendrocyte processes may be mediated by activation of FYN and suppression of RhoA GTPase. PMID:24741044

  16. Mutant Huntingtin Downregulates Myelin Regulatory Factor-Mediated Myelin Gene Expression and Affects Mature Oligodendrocytes

    PubMed Central

    Huang, Brenda; Wei, Wenjie; Wang, Guohao; Gaertig, Marta A.; Feng, Yue; Wang, Wei; Li, Xiao-Jiang; Li, Shihua

    2015-01-01

    SUMMARY Growing evidence indicates that non-neuronal mutant huntingtin toxicity plays an important role in Huntington’s disease (HD); however, whether and how mutant huntingtin affects oligodendrocytes, which are vitally important for neural function and axonal integrity, remain unclear. We first verified the presence of mutant huntingtin in oligodendrocytes in HD140Q knock-in mice. We then established transgenic mice (PLP-150Q) that selectively express mutant huntingtin in oligodendrocytes. PLP-150Q mice show progressive neurological symptoms and early death, as well as age-dependent demyelination and reduced expression of myelin genes that are downstream of myelin regulatory factor (MYRF or MRF), a transcriptional regulator that specifically activates and maintains the expression of myelin genes in mature oligodendrocytes. Consistently, mutant huntingtin binds abnormally to MYRF and affects its transcription activity. Our findings suggest that dysfunction of mature oligodendrocytes is involved in HD pathogenesis and may also make a good therapeutic target. PMID:25789755

  17. Mutant huntingtin downregulates myelin regulatory factor-mediated myelin gene expression and affects mature oligodendrocytes.

    PubMed

    Huang, Brenda; Wei, WenJie; Wang, Guohao; Gaertig, Marta A; Feng, Yue; Wang, Wei; Li, Xiao-Jiang; Li, Shihua

    2015-03-18

    Growing evidence indicates that non-neuronal mutant huntingtin toxicity plays an important role in Huntington's disease (HD); however, whether and how mutant huntingtin affects oligodendrocytes, which are vitally important for neural function and axonal integrity, remains unclear. We first verified the presence of mutant huntingtin in oligodendrocytes in HD140Q knockin mice. We then established transgenic mice (PLP-150Q) that selectively express mutant huntingtin in oligodendrocytes. PLP-150Q mice show progressive neurological symptoms and early death, as well as age-dependent demyelination and reduced expression of myelin genes that are downstream of myelin regulatory factor (MYRF or MRF), a transcriptional regulator that specifically activates and maintains the expression of myelin genes in mature oligodendrocytes. Consistently, mutant huntingtin binds abnormally to MYRF and affects its transcription activity. Our findings suggest that dysfunction of mature oligodendrocytes is involved in HD pathogenesis and may also make a good therapeutic target. PMID:25789755

  18. Recombinant TCR ligand induces tolerance to myelin oligodendrocyte glycoprotein 35-55 peptide and reverses clinical and histological signs of chronic experimental autoimmune encephalomyelitis in HLA-DR2 transgenic mice.

    PubMed

    Vandenbark, Arthur A; Rich, Cathleen; Mooney, Jeff; Zamora, Alex; Wang, Chunhe; Huan, Jianya; Fugger, Lars; Offner, Halina; Jones, Richard; Burrows, Gregory G

    2003-07-01

    In a previous study, we demonstrated that myelin oligodendrocyte glycoprotein (MOG)-35-55 peptide could induce severe chronic experimental autoimmune encephalomyelitis (EAE) in HLA-DR2(+) transgenic mice lacking all mouse MHC class II genes. We used this model to evaluate clinical efficacy and mechanism of action of a novel recombinant TCR ligand (RTL) comprised of the alpha(1) and beta(1) domains of DR2 (DRB1*1501) covalently linked to the encephalitogenic MOG-35-55 peptide (VG312). We found that the MOG/DR2 VG312 RTL could induce long-term tolerance to MOG-35-55 peptide and reverse clinical and histological signs of EAE in a dose- and peptide-dependent manner. Some mice treated with lower doses of VG312 relapsed after cessation of daily treatment, but the mice could be successfully re-treated with a higher dose of VG312. Treatment with VG312 strongly reduced secretion of Th1 cytokines (TNF-alpha and IFN-gamma) produced in response to MOG-35-55 peptide, and to a lesser degree purified protein derivative and Con A, but had no inhibitory effect on serum Ab levels to MOG-35-55 peptide. Abs specific for both the peptide and MHC moieties of the RTLs were also present after treatment with EAE, but these Abs had only a minor enhancing effect on T cell activation in vitro. These data demonstrate the powerful tolerance-inducing therapeutic effects of VG312 on MOG peptide-induced EAE in transgenic DR2 mice and support the potential of this approach to inhibit myelin Ag-specific responses in multiple sclerosis patients. PMID:12816990

  19. Astrocytic TIMP-1 Promotes Oligodendrocyte Differentiation and Enhances CNS Myelination

    PubMed Central

    Moore, Craig S.; Milner, Richard; Nishiyama, Akiko; Frausto, Ricardo F.; Serwanski, David R.; Pagarigan, Roberto R.; Whitton, J. Lindsay; Miller, Robert H.; Crocker, Stephen J.

    2011-01-01

    Tissue inhibitor of metalloproteinase-1 (TIMP-1) is an extracellular protein and endogenous regulator of matrix metalloproteinases (MMPs) secreted by astrocytes in response to CNS myelin injury. We have previously reported that adult TIMP-1KO mice exhibit poor myelin repair following demyelinating injury. This observation led us to hypothesize a role for TIMP-1 in oligodendrogenesis and CNS myelination. Herein, we demonstrate that compact myelin formation is significantly delayed in TIMP-1KO mice which coincided with dramatically reduced numbers of white matter astrocytes in the developing CNS. Analysis of differentiation in CNS progenitor cells (neurosphere) cultures from TIMP-1KO mice revealed a specific deficit of NG2+ oligodendrocyte progenitor cells. Application of rmTIMP-1 to TIMP-1KO neurosphere cultures evoked a dose-dependent increase in NG2+ cell numbers, while treatment with GM6001, a potent broad spectrum MMP inhibitor did not. Similarly, administration of recombinant murine TIMP-1 (rmTIMP-1) to A2B5+ immunopanned oligodendrocyte progenitors significantly increased the number of differentiated O1+ oligodendrocytes, while antisera to TIMP-1 reduced oligodendrocyte numbers. We also determined that A2B5+ oligodendrocyte progenitors grown in conditioned media derived from TIMP-1KO primary glial cultures resulted in reduced differentiation of mature O1+ oligodendrocytes. Finally, we report that addition of rmTIMP-1 to primary glial cultures resulted in a dose-dependent proliferative response of astrocytes. Together, these findings describe a previously uncharacterized role for TIMP-1 in the regulation of oligodendrocytes and astrocytes during development and provide a novel function for TIMP-1 on myelination in the developing CNS. PMID:21508247

  20. Cdon, a cell surface protein, mediates oligodendrocyte differentiation and myelination.

    PubMed

    Wang, Li-Chun; Almazan, Guillermina

    2016-06-01

    During central nervous system development, oligodendrocyte progenitors (OLPs) establish multiple branched processes and axonal contacts to initiate myelination. A complete understanding of the molecular signals implicated in cell surface interaction to initiate myelination/remyelination is currently lacking. The objective of our study was to assess whether Cdon, a cell surface protein that was shown to participate in muscle and neuron cell development, is involved in oligodendrocyte (OLG) differentiation and myelination. Here, we demonstrate that endogenous Cdon protein is expressed in OLPs, increasing in the early differentiation stages and decreasing in mature OLGs. Immunocytochemistry of endogenous Cdon showed localization on both OLG cell membranes and cellular processes exhibiting puncta- or varicosity-like structures. Cdon knockdown with siRNA decreased protein levels by 62% as well as two myelin-specific proteins, MBP and MAG. Conversely, overexpression of full-length rat Cdon increased myelin proteins in OLGs. The complexity of OLGs branching and contact point numbers with axons were also increased in Cdon overexpressing cells growing alone or in coculture with dorsal root ganglion neurons (DRGNs). Furthermore, myelination of DRGNs was decreased when OLPs were transfected with Cdon siRNA. Altogether, our results suggest that Cdon participates in OLG differentiation and myelination, most likely in the initial stages of development. GLIA 2016;64:1021-1033. PMID:26988125

  1. Damage to the Optic Chiasm in Myelin Oligodendrocyte Glycoprotein–Experimental Autoimmune Encephalomyelitis Mice

    PubMed Central

    Herrera, Sheryl L; Palmer, Vanessa L; Whittaker, Heather; Smith, Blair Cardigan; Kim, Annie; Schellenberg, Angela E; Thiessen, Jonathan D; Buist, Richard; Del Bigio, Marc R; Martin, Melanie

    2014-01-01

    Optic chiasm lesions in myelin oligodendrocyte glycoprotein (MOG)–experimental autoimmune encephalomyelitis (EAE) mice were characterized using magnetic resonance imaging (MRI) and validated using electron microscopy (EM). MR images were collected from 3 days after induction to remission, approximately 20 days after induction. Hematoxylin and eosin, solochrome cyanin–stained sections, and EM images were obtained from the optic chiasms of some mice approximately 4 days after disease onset when their scores were thought to be the highest. T2-weighted imaging and apparent diffusion coefficient map hyperintensities corresponded to abnormalities in the optic chiasms of EAE mice. Mixed inflammation was concentrated at the lateral surface. Degeneration of oligodendrocytes, myelin, and early axonal damage were also apparent. A marked increase in chiasm thickness was observed. T2-weighted and diffusion-weighted MRI can detect abnormalities in the optic chiasms of MOG-EAE mice. MRI is an important method in the study of this model toward understanding optic neuritis. PMID:25520558

  2. G protein-coupled receptor 37 is a negative regulator of oligodendrocyte differentiation and myelination

    PubMed Central

    Yang, Hyun-Jeong; Vainshtein, Anna; Maik-Rachline, Galia; Peles, Elior

    2016-01-01

    While the formation of myelin by oligodendrocytes is critical for the function of the central nervous system, the molecular mechanism controlling oligodendrocyte differentiation remains largely unknown. Here we identify G protein-coupled receptor 37 (GPR37) as an inhibitor of late-stage oligodendrocyte differentiation and myelination. GPR37 is enriched in oligodendrocytes and its expression increases during their differentiation into myelin forming cells. Genetic deletion of Gpr37 does not affect the number of oligodendrocyte precursor cells, but results in precocious oligodendrocyte differentiation and hypermyelination. The inhibition of oligodendrocyte differentiation by GPR37 is mediated by suppression of an exchange protein activated by cAMP (EPAC)-dependent activation of Raf-MAPK-ERK1/2 module and nuclear translocation of ERK1/2. Our data suggest that GPR37 regulates central nervous system myelination by controlling the transition from early-differentiated to mature oligodendrocytes. PMID:26961174

  3. DNA Methylation at the Neonatal State and at the Time of Diagnosis: Preliminary Support for an Association with the Estrogen Receptor 1, Gamma-Aminobutyric Acid B Receptor 1, and Myelin Oligodendrocyte Glycoprotein in Female Adolescent Patients with OCD

    PubMed Central

    Nissen, Judith Becker; Hansen, Christine Søholm; Starnawska, Anna; Mattheisen, Manuel; Børglum, Anders Dupont; Buttenschøn, Henriette Nørmølle; Hollegaard, Mads

    2016-01-01

    Obsessive–compulsive disorder (OCD) is a neuropsychiatric disorder. Non-genetic factors and their interaction with genes have attracted increasing attention. Epigenetics is regarded an important interface between environmental signals and activation/repression of genomic responses. Epigenetic mechanisms have not previously been examined in OCD in children and adolescents. The aim of the present study was to examine the DNA methylation profile of selected genes in blood spots from neonates later diagnosed with OCD and in the same children/adolescents at the time of diagnosis compared with age- and sex-matched controls. Furthermore, we wanted to characterize the association of the differential methylation profiles with the severity of OCD and treatment outcome. Dried and new blood spot samples were obtained from 21 female children/adolescents with verified OCD and 12 female controls. The differential methylation was analyzed using a linear model and the correlation with the severity of OCD and treatment outcome was analyzed using the Pearson correlation. We evaluated selected Illumina Infinium HumanMethylation450 BeadChip probes within and up to 100,000 bp up- and downstream of 14 genes previously associated with OCD (SLC1A1, SLC25A12, GABBR1, GAD1, DLGAP1, MOG, BDNF, OLIG2, NTRK2 and 3, ESR1, SL6A4, TPH2, and COMT). The study found no significantly differential methylation. However, preliminary support for a difference was found for the gamma-aminobutyric acid (GABA) B receptor 1 (cg10234998, cg17099072) in blood samples at birth and for the estrogen receptor 1 (ESR1) (cg10939667), the myelin oligodendrocyte glycoprotein (MOG) (cg16650906), and the brain-derived neurotrophic factor (BDNF) (cg14080521) in blood samples at the time of diagnosis. Preliminary support for an association was observed between the methylation profiles of GABBR1 and MOG and baseline severity, treatment effect, and responder status; and between the methylation profile of ESR1 and baseline

  4. DNA Methylation at the Neonatal State and at the Time of Diagnosis: Preliminary Support for an Association with the Estrogen Receptor 1, Gamma-Aminobutyric Acid B Receptor 1, and Myelin Oligodendrocyte Glycoprotein in Female Adolescent Patients with OCD.

    PubMed

    Nissen, Judith Becker; Hansen, Christine Søholm; Starnawska, Anna; Mattheisen, Manuel; Børglum, Anders Dupont; Buttenschøn, Henriette Nørmølle; Hollegaard, Mads

    2016-01-01

    Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder. Non-genetic factors and their interaction with genes have attracted increasing attention. Epigenetics is regarded an important interface between environmental signals and activation/repression of genomic responses. Epigenetic mechanisms have not previously been examined in OCD in children and adolescents. The aim of the present study was to examine the DNA methylation profile of selected genes in blood spots from neonates later diagnosed with OCD and in the same children/adolescents at the time of diagnosis compared with age- and sex-matched controls. Furthermore, we wanted to characterize the association of the differential methylation profiles with the severity of OCD and treatment outcome. Dried and new blood spot samples were obtained from 21 female children/adolescents with verified OCD and 12 female controls. The differential methylation was analyzed using a linear model and the correlation with the severity of OCD and treatment outcome was analyzed using the Pearson correlation. We evaluated selected Illumina Infinium HumanMethylation450 BeadChip probes within and up to 100,000 bp up- and downstream of 14 genes previously associated with OCD (SLC1A1, SLC25A12, GABBR1, GAD1, DLGAP1, MOG, BDNF, OLIG2, NTRK2 and 3, ESR1, SL6A4, TPH2, and COMT). The study found no significantly differential methylation. However, preliminary support for a difference was found for the gamma-aminobutyric acid (GABA) B receptor 1 (cg10234998, cg17099072) in blood samples at birth and for the estrogen receptor 1 (ESR1) (cg10939667), the myelin oligodendrocyte glycoprotein (MOG) (cg16650906), and the brain-derived neurotrophic factor (BDNF) (cg14080521) in blood samples at the time of diagnosis. Preliminary support for an association was observed between the methylation profiles of GABBR1 and MOG and baseline severity, treatment effect, and responder status; and between the methylation profile of ESR1 and baseline

  5. Organotypic Slice Cultures to Study Oligodendrocyte Dynamics and Myelination

    PubMed Central

    Hill, Robert A.; Medved, Jelena; Patel, Kiran D.; Nishiyama, Akiko

    2014-01-01

    NG2 expressing cells (polydendrocytes, oligodendrocyte precursor cells) are the fourth major glial cell population in the central nervous system. During embryonic and postnatal development they actively proliferate and generate myelinating oligodendrocytes. These cells have commonly been studied in primary dissociated cultures, neuron cocultures, and in fixed tissue. Using newly available transgenic mouse lines slice culture systems can be used to investigate proliferation and differentiation of oligodendrocyte lineage cells in both gray and white matter regions of the forebrain and cerebellum. Slice cultures are prepared from early postnatal mice and are kept in culture for up to 1 month. These slices can be imaged multiple times over the culture period to investigate cellular behavior and interactions. This method allows visualization of NG2 cell division and the steps leading to oligodendrocyte differentiation while enabling detailed analysis of region-dependent NG2 cell and oligodendrocyte functional heterogeneity. This is a powerful technique that can be used to investigate the intrinsic and extrinsic signals influencing these cells over time in a cellular environment that closely resembles that found in vivo. PMID:25177825

  6. Cytoskeletal Linker Protein Dystonin Is Not Critical to Terminal Oligodendrocyte Differentiation or CNS Myelination

    PubMed Central

    Bonin, Sawyer R.; Gibeault, Sabrina; De Repentigny, Yves; Kothary, Rashmi

    2016-01-01

    Oligodendrocyte differentiation and central nervous system myelination require massive reorganization of the oligodendrocyte cytoskeleton. Loss of specific actin- and tubulin-organizing factors can lead to impaired morphological and/or molecular differentiation of oligodendrocytes, resulting in a subsequent loss of myelination. Dystonin is a cytoskeletal linker protein with both actin- and tubulin-binding domains. Loss of function of this protein results in a sensory neuropathy called Hereditary Sensory Autonomic Neuropathy VI in humans and dystonia musculorum in mice. This disease presents with severe ataxia, dystonic muscle and is ultimately fatal early in life. While loss of the neuronal isoforms of dystonin primarily leads to sensory neuron degeneration, it has also been shown that peripheral myelination is compromised due to intrinsic Schwann cell differentiation abnormalities. The role of this cytoskeletal linker in oligodendrocytes, however, remains unclear. We sought to determine the effects of the loss of neuronal dystonin on oligodendrocyte differentiation and central myelination. To address this, primary oligodendrocytes were isolated from a severe model of dystonia musculorum, Dstdt-27J, and assessed for morphological and molecular differentiation capacity. No defects could be discerned in the differentiation of Dstdt-27J oligodendrocytes relative to oligodendrocytes from wild-type littermates. Survival was also compared between Dstdt-27J and wild-type oligodendrocytes, revealing no significant difference. Using a recently developed migration assay, we further analysed the ability of primary oligodendrocyte progenitor cell motility, and found that Dstdt-27J oligodendrocyte progenitor cells were able to migrate normally. Finally, in vivo analysis of oligodendrocyte myelination was done in phenotype-stage optic nerve, cerebral cortex and spinal cord. The density of myelinated axons and g-ratios of Dstdt-27J optic nerves was normal, as was myelin basic

  7. A zinc finger protein that regulates oligodendrocyte specification, migration and myelination in zebrafish.

    PubMed

    Sidik, Harwin; Talbot, William S

    2015-12-01

    Precise control of oligodendrocyte migration and development is crucial for myelination of axons in the central nervous system (CNS), but important questions remain unanswered about the mechanisms controlling these processes. In a zebrafish screen for myelination mutants, we identified a mutation in zinc finger protein 16-like (znf16l). znf16l mutant larvae have reduced myelin basic protein (mbp) expression and reduced CNS myelin. Marker, time-lapse and ultrastructural studies indicated that oligodendrocyte specification, migration and myelination are disrupted in znf16l mutants. Transgenic studies indicated that znf16l acts autonomously in oligodendrocytes. Expression of Zfp488 from mouse rescued mbp expression in znf16l mutants, indicating that these homologs have overlapping functions. Our results defined the function of a new zinc finger protein with specific function in oligodendrocyte specification, migration and myelination in the developing CNS. PMID:26459222

  8. Oligodendrocyte progenitor programming and reprogramming: Toward myelin regeneration.

    PubMed

    Lopez Juarez, Alejandro; He, Danyang; Richard Lu, Q

    2016-05-01

    Demyelinating diseases such as multiple sclerosis (MS) are among the most disabling and cost-intensive neurological disorders. The loss of myelin in the central nervous system, produced by oligodendrocytes (OLs), impairs saltatory nerve conduction, leading to motor and cognitive deficits. Immunosuppression therapy has a limited efficacy in MS patients, arguing for a paradigm shift to strategies that target OL lineage cells to achieve myelin repair. The inhibitory microenvironment in MS lesions abrogates the expansion and differentiation of resident OL precursor cells (OPCs) into mature myelin-forming OLs. Recent studies indicate that OPCs display a highly plastic ability to differentiate into alternative cell lineages under certain circumstances. Thus, understanding the mechanisms that maintain and control OPC fate and differentiation into mature OLs in a hostile, non-permissive lesion environment may open new opportunities for regenerative therapies. In this review, we will focus on 1) the plasticity of OPCs in terms of their developmental origins, distribution, and differentiation potentials in the normal and injured brain; 2) recent discoveries of extrinsic and intrinsic factors and small molecule compounds that control OPC specification and differentiation; and 3) therapeutic potential for motivation of neural progenitor cells and reprogramming of differentiated cells into OPCs and their likely impacts on remyelination. OL-based therapies through activating regenerative potentials of OPCs or cell replacement offer exciting opportunities for innovative strategies to promote remyelination and neuroprotection in devastating demyelinating diseases like MS. This article is part of a Special Issue entitled SI:NG2-glia(Invited only). PMID:26546966

  9. Role of transmembrane semaphorin Sema6A in oligodendrocyte differentiation and myelination.

    PubMed

    Bernard, Frédéric; Moreau-Fauvarque, Caroline; Heitz-Marchaland, Céline; Zagar, Yvrick; Dumas, Laura; Fouquet, Stéphane; Lee, Xinhua; Shao, Zhaohui; Mi, Sha; Chédotal, Alain

    2012-10-01

    Myelination is regulated by extracellular proteins, which control interactions between oligodendrocytes and axons. Semaphorins are repulsive axon guidance molecules, which control the migration of oligodendrocyte precursors during normal development and possibly in demyelinating diseases. We show here that the transmembrane semaphorin 6A (Sema6A) is highly expressed by myelinating oligodendrocytes in the postnatal mouse brain. In adult mice, Sema6A expression is upregulated in demyelinating lesions in cuprizone-treated mice. The analysis of the optic nerve and anterior commissure of Sema6A-deficient mice revealed a marked delay of oligodendrocyte differentiation. Accordingly, the development of the nodes of Ranvier is also transiently delayed. We also observed an arrest in the in vitro differentiation of purified oligodendrocytes lacking Sema6A, with a reduction of the expression level of Myelin Basic Protein. Their morphology is also abnormal, with less complex and ramified processes than wild-type oligodendrocytes. In myelinating co-cultures of dorsal root ganglion neurons and purified oligodendrocytes we found that myelination is perturbed in absence of Sema6A. These results suggest that Sema6A might have a role in myelination by controlling oligodendrocyte differentiation. PMID:22777942

  10. Autophagy Promotes Oligodendrocyte Survival and Function following Dysmyelination in a Long-Lived Myelin Mutant

    PubMed Central

    Smith, Chelsey M.; Mayer, Joshua A.; Duncan, Ian D.

    2014-01-01

    The Long–Evans shaker (les) rat has a mutation in myelin basic protein that results in severe CNS dysmyelination and subsequent demyelination during development. During this time, les oligodendrocytes accumulate cytoplasmic vesicles, including lysosomes and membrane-bound organelles. However, the mechanism and functional relevance behind these oligodendrocyte abnormalities in les have not been investigated. Using high-magnification electron microscopy, we identified the accumulations in les oligodendrocytes as early and late autophagosomes. Additionally, immunohistochemistry and Western blots showed an increase in autophagy markers in les. However, autophagy did not precede the death of les oligodendrocytes. Instead, upregulating autophagy promoted membrane extensions in les oligodendrocytes in vitro. Furthermore, upregulating autophagy in les rats via intermittent fasting increased the proportion of myelinated axons as well as myelin sheath thickness in les and control rats. Overall, this study provides insight into the abnormalities described in les as well as identifying a novel mechanism that promotes the survival and function of oligodendrocytes. PMID:23637198

  11. Adrenomedullin promotes differentiation of oligodendrocyte precursor cells into myelin-basic-protein expressing oligodendrocytes under pathological conditions in vitro

    PubMed Central

    Maki, Takakuni; Takahashi, Yoko; Miyamoto, Nobukazu; Liang, Anna C.; Ihara, Masafumi; Lo, Eng H.; Arai, Ken

    2015-01-01

    Oligodendrocytes, which are the main cell type in cerebral white matter, are generated from their precursor cells (oligodendrocyte precursor cells: OPCs). However, the differentiation from OPCs to oligodendrocytes is disturbed under stressed conditions. Therefore, drugs that can improve oligodendrocyte regeneration may be effective for white matter-related diseases. Here we show that a vasoactive peptide adrenomedullin (AM) promotes the in vitro differentiation of OPCs under pathological conditions. Primary OPCs were prepared from neonatal rat brains, and differentiated into myelin-basic-protein expressing oligodendrocytes over time. This in vitro OPC differentiation was inhibited by prolonged chemical hypoxic stress induced by non-lethal CoCl2 treatment. However, AM promoted the OPC differentiation under the hypoxic stress conditions, and the AM receptor antagonist AM22–52 cancelled the AM-induced OPC differentiation. In addition, AM treatment increased the phosphorylation level of Akt in OPC cultures, and correspondingly, the PI3K/Akt inhibitor LY294002 blocked the AM-induced OPC differentiation. Taken together, AM treatment rescued OPC maturation under pathological conditions via an AM-receptor-PI3K/Akt pathway. Oligodendrocytes play critical roles in white matter by forming myelin sheath. Therefore, AM signaling may be a promising therapeutic target to boost oligodendrocyte regeneration in CNS disorders. PMID:26002630

  12. Adrenomedullin promotes differentiation of oligodendrocyte precursor cells into myelin-basic-protein expressing oligodendrocytes under pathological conditions in vitro.

    PubMed

    Maki, Takakuni; Takahashi, Yoko; Miyamoto, Nobukazu; Liang, Anna C; Ihara, Masafumi; Lo, Eng H; Arai, Ken

    2015-07-01

    Oligodendrocytes, which are the main cell type in cerebral white matter, are generated from their precursor cells (oligodendrocyte precursor cells: OPCs). However, the differentiation from OPCs to oligodendrocytes is disturbed under stressed conditions. Therefore, drugs that can improve oligodendrocyte regeneration may be effective for white matter-related diseases. Here we show that a vasoactive peptide adrenomedullin (AM) promotes the in vitro differentiation of OPCs under pathological conditions. Primary OPCs were prepared from neonatal rat brains, and differentiated into myelin-basic-protein expressing oligodendrocytes over time. This in vitro OPC differentiation was inhibited by prolonged chemical hypoxic stress induced by non-lethal CoCl(2) treatment. However, AM promoted the OPC differentiation under the hypoxic stress conditions, and the AM receptor antagonist AM(22-52) canceled the AM-induced OPC differentiation. In addition, AM treatment increased the phosphorylation level of Akt in OPC cultures, and correspondingly, the PI3K/Akt inhibitor LY294002 blocked the AM-induced OPC differentiation. Taken together, AM treatment rescued OPC maturation under pathological conditions via an AM-receptor-PI3K/Akt pathway. Oligodendrocytes play critical roles in white matter by forming myelin sheath. Therefore, AM signaling may be a promising therapeutic target to boost oligodendrocyte regeneration in CNS disorders. PMID:26002630

  13. Oligodendrocyte, Astrocyte, and Microglia Crosstalk in Myelin Development, Damage, and Repair.

    PubMed

    Domingues, Helena S; Portugal, Camila C; Socodato, Renato; Relvas, João B

    2016-01-01

    Oligodendrocytes are the myelinating glia of the central nervous system. Myelination of axons allows rapid saltatory conduction of nerve impulses and contributes to axonal integrity. Devastating neurological deficits caused by demyelinating diseases, such as multiple sclerosis, illustrate well the importance of the process. In this review, we focus on the positive and negative interactions between oligodendrocytes, astrocytes, and microglia during developmental myelination and remyelination. Even though many lines of evidence support a crucial role for glia crosstalk during these processes, the nature of such interactions is often neglected when designing therapeutics for repair of demyelinated lesions. Understanding the cellular and molecular mechanisms underlying glial cell communication and how they influence oligodendrocyte differentiation and myelination is fundamental to uncover novel therapeutic strategies for myelin repair. PMID:27551677

  14. Oligodendrocyte, Astrocyte, and Microglia Crosstalk in Myelin Development, Damage, and Repair

    PubMed Central

    Domingues, Helena S.; Portugal, Camila C.; Socodato, Renato; Relvas, João B.

    2016-01-01

    Oligodendrocytes are the myelinating glia of the central nervous system. Myelination of axons allows rapid saltatory conduction of nerve impulses and contributes to axonal integrity. Devastating neurological deficits caused by demyelinating diseases, such as multiple sclerosis, illustrate well the importance of the process. In this review, we focus on the positive and negative interactions between oligodendrocytes, astrocytes, and microglia during developmental myelination and remyelination. Even though many lines of evidence support a crucial role for glia crosstalk during these processes, the nature of such interactions is often neglected when designing therapeutics for repair of demyelinated lesions. Understanding the cellular and molecular mechanisms underlying glial cell communication and how they influence oligodendrocyte differentiation and myelination is fundamental to uncover novel therapeutic strategies for myelin repair. PMID:27551677

  15. Oligodendrocyte development and the onset of myelination in the human fetal brain.

    PubMed

    Jakovcevski, Igor; Filipovic, Radmila; Mo, Zhicheng; Rakic, Sonja; Zecevic, Nada

    2009-01-01

    Oligodendrocytes are cells that myelinate axons, providing saltatory conduction of action potentials and proper function of the central nervous system. Myelination begins prenatally in the human, and the sequence of oligodendrocyte development and the onset of myelination are not thoroughly investigated. This knowledge is important to better understand human diseases, such as periventricular leukomalacia, one of the leading causes of motor deficit in premature babies, and demyelinating disorders such as multiple sclerosis (MS). In this review we discuss the spatial and temporal progression of oligodendrocyte lineage characterized by the expression of specific markers and transcription factors in the human fetal brain from the early embryonic period (5 gestational weeks, gw) until midgestation (24 gw). Our in vitro evidence indicated that a subpopulation of human oligodendrocytes may have dorsal origin, from cortical radial glia cells, in addition to their ventral telencephalic origin. Furthermore, we demonstrated that the regulation of myelination in the human fetal brain includes positive and negative regulators. Chemokines, such as CXCL1, abundant in proliferative zones during brain development and in regions of remyelination in adult, are discussed in the view of their potential roles in stimulating oligodendrocyte development. Other signals are inhibitory and may include, but are not limited to, polysialic acid modification of the neural cell adhesion molecule on axons. Overall, important differences in temporal and spatial distribution and regulatory signals for oligodendrocyte differentiation exist between human and rodent brains. Those differences may underlie the unique susceptibility of humans to demyelinating diseases, such as MS. PMID:19521542

  16. Movement and structure of mitochondria in oligodendrocytes and their myelin sheaths.

    PubMed

    Rinholm, Johanne E; Vervaeke, Koen; Tadross, Michael R; Tkachuk, Ariana N; Kopek, Benjamin G; Brown, Timothy A; Bergersen, Linda H; Clayton, David A

    2016-05-01

    Mitochondria play several crucial roles in the life of oligodendrocytes. During development of the myelin sheath they are essential providers of carbon skeletons and energy for lipid synthesis. During normal brain function their consumption of pyruvate will be a key determinant of how much lactate is available for oligodendrocytes to export to power axonal function. Finally, during calcium-overload induced pathology, as occurs in ischemia, mitochondria may buffer calcium or induce apoptosis. Despite their important functions, very little is known of the properties of oligodendrocyte mitochondria, and mitochondria have never been observed in the myelin sheaths. We have now used targeted expression of fluorescent mitochondrial markers to characterize the location and movement of mitochondria within oligodendrocytes. We show for the first time that mitochondria are able to enter and move within the myelin sheath. Within the myelin sheath the highest number of mitochondria was in the cytoplasmic ridges along the sheath. Mitochondria moved more slowly than in neurons and, in contrast to their behavior in neurons and astrocytes, their movement was increased rather than inhibited by glutamate activating NMDA receptors. By electron microscopy we show that myelin sheath mitochondria have a low surface area of cristae, which suggests a low ATP production. These data specify fundamental properties of the oxidative phosphorylation system in oligodendrocytes, the glial cells that enhance cognition by speeding action potential propagation and provide metabolic support to axons. GLIA 2016;64:810-825. PMID:26775288

  17. Leukemia inhibitory factor regulates the timing of oligodendrocyte development and myelination in the postnatal optic nerve

    PubMed Central

    Ishibashi, Tomoko; Lee, Philip R.; Baba, Hiroko; Fields, R. Douglas

    2009-01-01

    Leukemia inhibitory factor (LIF) promotes the survival of oligodendrocytes both in vitro and in an animal model of multiple sclerosis, but the possible role of LIF signaling in myelination during normal development has not been investigated. We find that LIF-/- mice have a pronounced myelination defect in optic nerve at postnatal day 10. Myelin basic protein (MBP)- and proteolipid protein (PLP)-positive myelin was evident throughout the optic nerve in the wild-type mice, but staining was present only at the chiasmal region in LIF-/- mice of the same age. Further experiments suggest that the myelination defect was a consequence of a delay in maturation of oligodendrocyte precursor cell (OPC) population. The number of Olig2-positive cells was dramatically decreased in optic nerve of LIF-/- mice, and the distribution of Olig2-positive cells was restricted to the chiasmal region of the nerve in a steep gradient toward the retina. Gene expression profiling and cell culture experiments revealed that OPCs from P10 optic nerve of LIF-/- mice remained in a highly proliferative immature stage compared with littermate controls. Interestingly, by postnatal day 14, MBP immunostaining in the LIF-/- optic nerve was comparable to that of LIF+/+ mice. These results suggest that, during normal development of mouse optic nerve, there is a defined developmental time window when LIF is required for correct myelination. Myelination seems to recover by postnatal day 14, so LIF is not necessary for the completion of myelination during postnatal development. PMID:19598242

  18. Oligodendrocytes expressing exclusively the DM20 isoform of the proteolipid protein gene: myelination and development.

    PubMed

    Spörkel, Olaf; Uschkureit, Thomas; Büssow, Heinrich; Stoffel, Wilhelm

    2002-01-01

    Oligodendroglia and Schwann cells synthesize myelin-specific proteins and lipids for the assembly of the highly organized myelin membrane of the motor-sensory axons in the central (CNS) and peripheral nervous system (PNS), respectively, allowing rapid saltatory conduction. The isoforms of the main myelin proteins, the peripheral myelin basic isoproteins (MBP) and the integral proteolipid proteins, PLP and DM20, arise from alternative splicing. Activation of a cryptic splice site in exon III of plp leads to the deletion of 105 bp encoding the PLP-specific 35 amino acid residues within the cytosolic loop 3 of the four-transmembrane domain (TMD) integral membrane protein. To study the different proposed functions of DM20 during the development of oligodendrocytes and in myelination, we targeted the plp locus in embryonic stem cells by homologous recombination by a construct, which allows solely the expression of the DM20 specific exon III sequence. The resulting dm20(only) mouse line expresses exclusively DM20 isoprotein, which is functionally assembled into the membrane, forming a highly ordered and tightly compacted myelin sheath. The truncated cytosolic loop devoid of the PLP-specific 35 amino acid residues, including two thioester groups, had no impact on the periodicity of CNS myelin. In contrast to the PLP/DM20-deficient mouse, mutant CNS of dm20(only) mice showed no axonal swellings and neurodegeneration but a slow punctuated disintegration of the compact layers of the myelin sheath and a rare oligodendrocyte death developing with aging. PMID:11746780

  19. Sonic hedgehog and neurotrophin-3 increase oligodendrocyte numbers and myelination after spinal cord injury

    PubMed Central

    Goodman, Ashley G.; Kukushliev, Todor V.; Hassani, Donna M.; Cummings, Brian J.; Anderson, Aileen J.; Shea, Lonnie D.

    2014-01-01

    Spinal cord injury (SCI) results in loss of sensory and motor function below the level of injury and has limited available therapies. Multiple channel bridges have been investigated as a means to create a permissive environment for regeneration, with channels supporting axonal growth through the injury. Bridges support robust axon growth with myelination of the axons, and herein we investigated the cell types that are myelinating the axons and whether trophic factors can enhance myelination. Lentivirus encoding for neurotrophin-3 (NT3), sonic hedgehog (SHH) and the combination of these factors was delivered from bridges implanted into a lateral hemisection defect at T9/T10 in mice, and the response of endogenous progenitor cells within the spinal cord was investigated. Relative to control, the localized sustained expression of these factors significantly increased growth of regenerating axons into the bridge and enhanced axon myelination 8 weeks after injury. SHH decreased Sox2+ cells and increased Olig2+ cells, whereas NT3 alone or in combination with SHH enhanced GFAP+ and Olig2+ cells relative to control. For delivery of lentivirus encoding for either factor, we identified cells at various stages of differentiation along the oligodendrocyte lineage (e.g., O4+, GalC+). Expression of NT3 enhanced myelination primarily by infiltrating Schwann cells, whereas SHH over-expression substantially increased myelination by oligodendrocytes. Gene delivery represents a promising tool to direct activation and differentiation of endogenous progenitor cells for applications in regenerative medicine. PMID:24873988

  20. LINGO-1, a Transmembrane Signaling Protein, Inhibits Oligodendrocyte Differentiation and Myelination through Intercellular Self-interactions

    PubMed Central

    Jepson, Scott; Vought, Bryan; Gross, Christian H.; Gan, Lu; Austen, Douglas; Frantz, J. Daniel; Zwahlen, Jacque; Lowe, Derek; Markland, William; Krauss, Raul

    2012-01-01

    Overcoming remyelination failure is a major goal of new therapies for demyelinating diseases like multiple sclerosis. LINGO-1, a key negative regulator of myelination, is a transmembrane signaling protein expressed in both neurons and oligodendrocytes. In neurons, LINGO-1 is an integral component of the Nogo receptor complex, which inhibits axonal growth via RhoA. Because the only ligand-binding subunit of this complex, the Nogo receptor, is absent in oligodendrocytes, the extracellular signals that inhibit myelination through a LINGO-1-mediated mechanism are unknown. Here we show that LINGO-1 inhibits oligodendrocyte terminal differentiation through intercellular interactions and is capable of a self-association in trans. Consistent with previous reports, overexpression of full-length LINGO-1 inhibited differentiation of oligodendrocyte precursor cells (OPCs). Unexpectedly, treatment with a soluble recombinant LINGO-1 ectodomain also had an inhibitory effect on OPCs and decreased myelinated axonal segments in cocultures with neurons from dorsal root ganglia. We demonstrated LINGO-1-mediated inhibition of OPCs through intercellular signaling by using a surface-bound LINGO-1 construct expressed ectopically in astrocytes. Further investigation showed that the soluble LINGO-1 ectodomain can interact with itself in trans by binding to CHO cells expressing full-length LINGO-1. Finally, we observed that soluble LINGO-1 could activate RhoA in OPCs. We propose that LINGO-1 acts as both a ligand and a receptor and that the mechanism by which it negatively regulates OPC differentiation and myelination is mediated by a homophilic intercellular interaction. Disruption of this protein-protein interaction could lead to a decrease of LINGO-1 inhibition and an increase in myelination. PMID:22514275

  1. LINGO-1, a transmembrane signaling protein, inhibits oligodendrocyte differentiation and myelination through intercellular self-interactions.

    PubMed

    Jepson, Scott; Vought, Bryan; Gross, Christian H; Gan, Lu; Austen, Douglas; Frantz, J Daniel; Zwahlen, Jacque; Lowe, Derek; Markland, William; Krauss, Raul

    2012-06-22

    Overcoming remyelination failure is a major goal of new therapies for demyelinating diseases like multiple sclerosis. LINGO-1, a key negative regulator of myelination, is a transmembrane signaling protein expressed in both neurons and oligodendrocytes. In neurons, LINGO-1 is an integral component of the Nogo receptor complex, which inhibits axonal growth via RhoA. Because the only ligand-binding subunit of this complex, the Nogo receptor, is absent in oligodendrocytes, the extracellular signals that inhibit myelination through a LINGO-1-mediated mechanism are unknown. Here we show that LINGO-1 inhibits oligodendrocyte terminal differentiation through intercellular interactions and is capable of a self-association in trans. Consistent with previous reports, overexpression of full-length LINGO-1 inhibited differentiation of oligodendrocyte precursor cells (OPCs). Unexpectedly, treatment with a soluble recombinant LINGO-1 ectodomain also had an inhibitory effect on OPCs and decreased myelinated axonal segments in cocultures with neurons from dorsal root ganglia. We demonstrated LINGO-1-mediated inhibition of OPCs through intercellular signaling by using a surface-bound LINGO-1 construct expressed ectopically in astrocytes. Further investigation showed that the soluble LINGO-1 ectodomain can interact with itself in trans by binding to CHO cells expressing full-length LINGO-1. Finally, we observed that soluble LINGO-1 could activate RhoA in OPCs. We propose that LINGO-1 acts as both a ligand and a receptor and that the mechanism by which it negatively regulates OPC differentiation and myelination is mediated by a homophilic intercellular interaction. Disruption of this protein-protein interaction could lead to a decrease of LINGO-1 inhibition and an increase in myelination. PMID:22514275

  2. Loss of Myelin-Associated Glycoprotein in Kearns-Sayre Syndrome

    PubMed Central

    Lax, Nichola Z.; Campbell, Graham R.; Reeve, Amy K.; Ohno, Nobuhiko; Zambonin, Jessica; Blakely, Emma L.; Taylor, Robert W.; Bonilla, Eduardo; Tanji, Kurenai; DiMauro, Salvatore; Jaros, Evelyn; Lassmann, Hans; Turnbull, Doug M.; Mahad, Don J.

    2013-01-01

    Objective To explore myelin components and mitochondrial changes within the central nervous system in patients with well-characterized mitochondrial disorders due to nuclear DNA or mitochondrial DNA (mtDNA) mutations. Design Immunohistochemical analysis, histochemical analysis, mtDNA sequencing, and real-time and long-range polymerase chain reaction were used to determine the pathogenicity of mtDNA deletions. Setting Department of Clinical Pathology, Columbia University Medical Center, and Newcastle Brain Tissue Resource. Patients Seventeen patients with mitochondrial disorders and 7 controls were studied from August 1, 2009, to August 1, 2010. Main Outcome Measure Regions of myelin-associated glycoprotein (MAG) loss. Results Myelin-associated glycoprotein loss in Kearns-Sayre syndrome was associated with oligodendrocyte loss and nuclear translocation of apoptosis-inducing factor, whereas inflammation, neuronal loss, and axonal injury were minimal. In a Kearns-Sayre syndrome MAG loss region, high levels of mtDNA deletions together with cytochrome- c oxidase–deficient cells and loss of mitochondrial respiratory chain subunits (more prominent in the white than gray matter and glia than axons) confirmed the pathogenicity of mtDNA deletions. Conclusion Primary mitochondrial respiratory chain defects affecting the white matter, and unrelated to inflammation, are associated with MAG loss and central nervous system demyelination. PMID:22491194

  3. Different Mechanisms Regulate Expression of Zebrafish Myelin Protein Zero (P0) in Myelinating Oligodendrocytes and Its Induction following Axonal Injury*

    PubMed Central

    Bai, Qing; Parris, Ritika S.; Burton, Edward A.

    2014-01-01

    Zebrafish CNS axons regenerate robustly following injury; it is thought that CNS oligodendrocytes contribute to this response by expressing growth-promoting molecules. We characterized the mpz gene, which encodes myelin protein zero and is up-regulated in oligodendroglia following axonal injury. The 2.5-kb mpz mRNA is expressed from a single TATA box promoter. Four independent Tg(mpz:egfp) transgenic zebrafish lines, in which GFP was expressed under the mpz promoter and 10 kb of genomic 5′-flanking sequence, showed transgene expression in CNS oligodendrocytes from larval development through adulthood. Following optic nerve crush injury, the mpz:egfp transgene was strongly up-regulated in oligodendrocytes along the regenerating retinotectal projection, mirroring up-regulation of endogenous mpz mRNA. GFP-expressing oligodendroglia were significantly more abundant in the regenerating optic pathway, resulting from both transgene induction in oligodendroglial precursors and the birth of new cells. Up-regulation of the mpz:egfp transgene was not dependent on axonal regeneration, suggesting that the primary signal may be axonal loss, debris, or microglial infiltration. Deletion experiments indicated that an oligodendroglial enhancer located in the region from −6 to −10 kb with respect to the mpz transcriptional start site is dissociable from the cis-regulatory element mediating the mpz transcriptional response to axonal injury, which is located between −1 and −4 kb. These data show that different mechanisms regulate expression of zebrafish mpz in myelinating oligodendrocytes and its induction following axonal injury. The underlying molecular events could potentially be exploited to enhance axonal repair following mammalian CNS injury. The transgenic lines and cis-regulatory constructs reported here will facilitate identification of the relevant signaling pathways. PMID:25028515

  4. Transcriptional Expression of Myelin Basic Protein in Oligodendrocytes Depends on Functional Syntaxin 4: a Potential Correlation with Autocrine Signaling

    PubMed Central

    Bijlard, Marjolein; Klunder, Bert; de Jonge, Jenny C.; Nomden, Anita; Tyagi, Sanjay; de Vries, Hans; Hoekstra, Dick

    2014-01-01

    Myelination of axons by oligodendrocytes is essential for saltatory nerve conduction. To form myelin membranes, a coordinated synthesis and subsequent polarized transport of myelin components are necessary. Here, we show that as part of the mechanism to establish membrane polarity, oligodendrocytes exploit a polarized distribution of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) machinery components syntaxins 3 and 4, localizing to the cell body and the myelin membrane, respectively. Our data further reveal that the expression of myelin basic protein (MBP), a myelin-specific protein that is synthesized “on site” after transport of its mRNA, depends on the correct functioning of the SNARE machinery, which is not required for mRNA granule assembly and transport per se. Thus, downregulation and overexpression of syntaxin 4 but not syntaxin 3 in oligodendrocyte progenitor cells but not immature oligodendrocytes impeded MBP mRNA transcription, thereby preventing MBP protein synthesis. The expression and localization of another myelin-specific protein, proteolipid protein (PLP), was unaltered. Strikingly, conditioned medium obtained from developing oligodendrocytes was able to rescue the block of MBP mRNA transcription in syntaxin 4-downregulated cells. These findings indicate that the initiation of the biosynthesis of MBP mRNA relies on a syntaxin 4-dependent mechanism, which likely involves activation of an autocrine signaling pathway. PMID:25512606

  5. Transcriptional expression of myelin basic protein in oligodendrocytes depends on functional syntaxin 4: a potential correlation with autocrine signaling.

    PubMed

    Bijlard, Marjolein; Klunder, Bert; de Jonge, Jenny C; Nomden, Anita; Tyagi, Sanjay; de Vries, Hans; Hoekstra, Dick; Baron, Wia

    2015-02-01

    Myelination of axons by oligodendrocytes is essential for saltatory nerve conduction. To form myelin membranes, a coordinated synthesis and subsequent polarized transport of myelin components are necessary. Here, we show that as part of the mechanism to establish membrane polarity, oligodendrocytes exploit a polarized distribution of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) machinery components syntaxins 3 and 4, localizing to the cell body and the myelin membrane, respectively. Our data further reveal that the expression of myelin basic protein (MBP), a myelin-specific protein that is synthesized "on site" after transport of its mRNA, depends on the correct functioning of the SNARE machinery, which is not required for mRNA granule assembly and transport per se. Thus, downregulation and overexpression of syntaxin 4 but not syntaxin 3 in oligodendrocyte progenitor cells but not immature oligodendrocytes impeded MBP mRNA transcription, thereby preventing MBP protein synthesis. The expression and localization of another myelin-specific protein, proteolipid protein (PLP), was unaltered. Strikingly, conditioned medium obtained from developing oligodendrocytes was able to rescue the block of MBP mRNA transcription in syntaxin 4-downregulated cells. These findings indicate that the initiation of the biosynthesis of MBP mRNA relies on a syntaxin 4-dependent mechanism, which likely involves activation of an autocrine signaling pathway. PMID:25512606

  6. Divergent Role for MMP-2 in Myelin Breakdown and Oligodendrocyte Death Following Transient Global Ischemia

    PubMed Central

    Walker, Espen J.; Rosenberg, Gary A.

    2016-01-01

    Transient global ischemia causes delayed white matter injury to the brain with oligodendrocyte (OLG) death and myelin breakdown. There is increasing evidence that hypoxia may be involved in several diseases of the white matter, including multiple sclerosis, vascular dementia, and ischemia. Matrix metalloproteinases (MMPs) are increased in rat and mouse models of hypoxic hypoperfusion and have been associated with OLG death. However, whether the MMPs act on myelin or OLGs remains unresolved. We hypothesized that delayed expression of MMPs caused OLG death and myelin breakdown. To test the hypothesis, adult mice underwent hypoxic hypoperfusion with transient bilateral occlusion of the carotid arteries. After 3 days of reperfusion, ischemic white matter had increased reactivity of astrocytes and microglia, MMP-2 localization in astrocytes, and increased protein expression and activity of MMP-2. In addition, there was a significant loss of myelin basic protein (MBP) by Western blot and caspase-3- mediated OLG death. Treatment with the broad-spectrum MMP inhibitor, BB-94, significantly decreased astrocyte reactivity and MMP-2 activity. More importantly, it reduced MBP breakdown. However, MMP inhibition had no effect on OLG loss. Our results implicate MMPs released by reactive astrocytes in delayed myelin degradation, while OLG death occurs by an MMP-independent mechanism. We propose that MMP-mediated myelin loss is important in hypoxic injury to the white matter. PMID:19830840

  7. Exposure to serotonin adversely affects oligodendrocyte development and myelination in vitro.

    PubMed

    Fan, Lir-Wan; Bhatt, Abhay; Tien, Lu-Tai; Zheng, Baoying; Simpson, Kimberly L; Lin, Rick C S; Cai, Zhengwei; Kumar, Praveen; Pang, Yi

    2015-05-01

    Serotonin (5-hydroxytryptamine, 5-HT) has been implicated to play critical roles in early neural development. Recent reports have suggested that perinatal exposure to selective serotonin reuptake inhibitors (SSRIs) resulted in cortical network miswiring, abnormal social behavior, callosal myelin malformation, as well as oligodendrocyte (OL) pathology in rats. To gain further insight into the cellular and molecular mechanisms underlying SSRIs-induced OL and myelin abnormalities, we investigated the effect of 5-HT exposure on OL development, cell death, and myelination in cell culture models. First, we showed that 5-HT receptor 1A and 2A subtypes were expressed in OL lineages, using immunocytochemistry, Western blot, as well as intracellular Ca(2+) measurement. We then assessed the effect of serotonin exposure on the lineage development, expression of myelin proteins, cell death, and myelination, in purified OL and neuron-OL myelination cultures. For pure OL cultures, our results showed that 5-HT exposure led to disturbance of OL development, as indicated by aberrant process outgrowth and reduced myelin proteins expression. At higher doses, such exposure triggered a development-dependent cell death, as immature OLs exhibited increasing susceptibility to 5-HT treatment compared to OL progenitor cells (OPC). We showed further that 5-HT-induced immature OL death was mediated at least partially via 5-HT2A receptor, since cell death could be mimicked by 5-HT2A receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride, (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride, but atten-uated by pre-treatment with 5-HT2A receptor antagonist ritanserin. Utilizing a neuron-OL myelination co-culture model, our data showed that 5-HT exposure significantly reduced the number of myelinated internodes. In contrast to cell injury observed in pure OL cultures, 5-HT exposure did not lead to OL death or reduced OL density in neuron-OL co-cultures. However, abnormal

  8. The tetraspanin, KAI1/CD82, is expressed by late-lineage oligodendrocyte precursors and may function to restrict precursor migration and promote oligodendrocyte differentiation and myelination

    PubMed Central

    Mela, Angeliki; Goldman, James E.

    2009-01-01

    In the adult mammalian brain, oligodendrocyte progenitors can differentiate into mature oligodendrocytes during remyelination. Mechanisms that regulate migration and differentiation of progenitors are of great importance in understanding normal development and demyelinating/remyelinating conditions. In a microarray analysis comparing adult and neonatal O4+ cells, we found that the tetraspanin, KAI1/CD82, is far more highly expressed in adult O4+ cells than in neonatal O4+ cells (Lin et al., in press). CD82 is a metastasis suppressor and its expression is often down-regulated or lost in the advanced stages of metastatic cancer. We hypothesized that CD82 could be a factor that restricts migration and promotes differentiation of maturing oligodendrocytes. Western analysis of isolated adult O4+ cells confirms the elevated levels of CD82, which continues to be expressed as these become O1+ in vitro. In the adult rat white matter CD82 is co-expressed with CC1 and olig2 but not with NG2 or GFAP. Immature cells of the neonatal forebrain subventricular zone (SVZ) infected in vivo with a retrovirus that constitutively expresses CD82 do not remain immature, but differentiate either into CC1+ and MBP+ myelinating oligodendrocytes in the white matter or zebrinII+ astrocytes in the cortex. Their migration from the SVZ is severely restricted. In contrast, downregulation of CD82 in SVZ cells in vivo, using retroviral-expressed shRNAs, prevents their differentiation into myelinating oligodendrocytes. shRNA-expressing cells remained PDGFRα+, olig2+ or NG2+, or became CC1+ non-myelinating oligodendrocytes, or GFAP+ astrocytes. CD82 thus appears to be a critical molecule in the regulation of oligodendrocyte progenitor migration and myelination. PMID:19741124

  9. Genetically induced adult oligodendrocyte cell death is associated with poor myelin clearance, reduced remyelination, and axonal damage.

    PubMed

    Pohl, Hartmut B F; Porcheri, Cristina; Mueggler, Thomas; Bachmann, Lukas C; Martino, Gianvito; Riethmacher, Dieter; Franklin, Robin J M; Rudin, Markus; Suter, Ueli

    2011-01-19

    Loss of oligodendrocytes is a feature of many demyelinating diseases including multiple sclerosis. Here, we have established and characterized a novel model of genetically induced adult oligodendrocyte death. Specific primary loss of adult oligodendrocytes leads to a well defined and highly reproducible course of disease development that can be followed longitudinally by magnetic resonance imaging. Histological and ultrastructural analyses revealed progressive myelin vacuolation, in parallel to disease development that includes motor deficits, tremor, and ataxia. Myelin damage and clearance were associated with induction of oligodendrocyte precursor cell proliferation, albeit with some regional differences. Remyelination was present in the mildly affected corpus callosum. Consequences of acutely induced cell death of adult oligodendrocytes included secondary axonal damage. Microglia were activated in affected areas but without significant influx of B-cells, T-helper cells, or T-cytotoxic cells. Analysis of the model on a RAG-1 (recombination activating gene-1)-deficient background, lacking functional lymphocytes, did not change the observed disease and pathology compared with immune-competent mice. We conclude that this model provides the opportunity to study the consequences of adult oligodendrocyte death in the absence of primary axonal injury and reactive cells of the adaptive immune system. Our results indicate that if the blood-brain barrier is not disrupted, myelin debris is not removed efficiently, remyelination is impaired, and axonal integrity is compromised, likely as the result of myelin detachment. This model will allow the evaluation of strategies aimed at improving remyelination to foster axon protection. PMID:21248132

  10. Dorsally- and ventrally-derived oligodendrocytes have similar electrical properties but myelinate preferred tracts

    PubMed Central

    Kessaris, Nicoletta; Anderson, Patrick N; Attwell, David; Richardson, William D

    2014-01-01

    In the developing spinal cord most oligodendrocyte precursors (OLPs) arise from the ventral ventricular zone (VZ) under the influence of Sonic Hedgehog but a minority is generated from the dorsal VZ in a Hedgehog-independent manner. In the developing forebrain too, OLPs arise from both the ventral and the dorsal VZ. It is not known whether dorsally- and ventrally- derived oligodendrocyte (OL) lineage cells have different properties. We generated a dual reporter mouse line to color code ventrally- and dorsally-derived OLPs (vOLPs and dOLPs) and their differentiated oligodendrocyte progeny (vOLs and dOLs) for functional studies. We found that ~80% of OL lineage cells in the postnatal spinal cord and ~20% in the corpus callosum are ventrally-derived. In both spinal cord and corpus callosum, vOLPs and dOLPs had indistinguishable electrical properties, as did vOLs and dOLs. However, vOLPs and dOLPs had different migration and settling patterns. In the spinal cord, vOLPs appeared early and spread uniformly throughout the cord whereas dOLPs arrived later and remained mainly in the dorsal and dorsolateral funiculi. During adulthood, corticospinal and rubrospinal tracts became myelinated mainly by dOLs, even though vOLs dominated these tracts during early postnatal life. Thus, dOLPs are electrically similar to vOLPs but appear to out-compete them for dorsal axons. PMID:21543611

  11. Loss of lysophosphatidic acid receptor LPA1 alters oligodendrocyte differentiation and myelination in the mouse cerebral cortex.

    PubMed

    García-Díaz, Beatriz; Riquelme, Raquel; Varela-Nieto, Isabel; Jiménez, Antonio Jesús; de Diego, Isabel; Gómez-Conde, Ana Isabel; Matas-Rico, Elisa; Aguirre, José Ángel; Chun, Jerold; Pedraza, Carmen; Santín, Luis Javier; Fernández, Oscar; Rodríguez de Fonseca, Fernando; Estivill-Torrús, Guillermo

    2015-11-01

    Lysophosphatidic acid (LPA) is an intercellular signaling lipid that regulates multiple cellular functions, acting through specific G-protein coupled receptors (LPA(1-6)). Our previous studies using viable Malaga variant maLPA1-null mice demonstrated the requirement of the LPA1 receptor for normal proliferation, differentiation, and survival of the neuronal precursors. In the cerebral cortex LPA1 is expressed extensively in differentiating oligodendrocytes, in parallel with myelination. Although exogenous LPA-induced effects have been investigated in myelinating cells, the in vivo contribution of LPA1 to normal myelination remains to be demonstrated. This study identified a relevant in vivo role for LPA1 as a regulator of cortical myelination. Immunochemical analysis in adult maLPA1-null mice demonstrated a reduction in the steady-state levels of the myelin proteins MBP, PLP/DM20, and CNPase in the cerebral cortex. The myelin defects were confirmed using magnetic resonance spectroscopy and electron microscopy. Stereological analysis limited the defects to adult differentiating oligodendrocytes, without variation in the NG2+ precursor cells. Finally, a possible mechanism involving oligodendrocyte survival was demonstrated by the impaired intracellular transport of the PLP/DM20 myelin protein which was accompanied by cellular loss, suggesting stress-induced apoptosis. These findings describe a previously uncharacterized in vivo functional role for LPA1 in the regulation of oligodendrocyte differentiation and myelination in the CNS, underlining the importance of the maLPA1-null mouse as a model for the study of demyelinating diseases. PMID:25226845

  12. Anosmin-1 over-expression regulates oligodendrocyte precursor cell proliferation, migration and myelin sheath thickness.

    PubMed

    Murcia-Belmonte, Verónica; Esteban, Pedro F; Martínez-Hernández, José; Gruart, Agnès; Luján, Rafael; Delgado-García, José María; de Castro, Fernando

    2016-04-01

    During development of the central nervous system, anosmin-1 (A1) works as a chemotropic cue contributing to axonal outgrowth and collateralization, as well as modulating the migration of different cell types, fibroblast growth factor receptor 1 (FGFR1) being the main receptor involved in all these events. To further understand the role of A1 during development, we have analysed the over-expression of human A1 in a transgenic mouse line. Compared with control mice during development and in early adulthood, A1 over-expressing transgenic mice showed an enhanced oligodendrocyte precursor cell (OPC) proliferation and a higher number of OPCs in the subventricular zone and in the corpus callosum (CC). The migratory capacity of OPCs from the transgenic mice is increased in vitro due to a higher basal activation of ERK1/2 mediated through FGFR1 and they also produced more myelin basic protein (MBP). In vivo, the over-expression of A1 resulted in an elevated number of mature oligodendrocytes with higher levels of MBP mRNA and protein, as well as increased levels of activation of the ERK1/2 proteins, while electron microscopy revealed thicker myelin sheaths around the axons of the CC in adulthood. Also in the mature CC, the nodes of Ranvier were significantly longer and the conduction velocity of the nerve impulse in vivo was significantly increased in the CC of A1 over-expressing transgenic mice. Altogether, these data confirmed the involvement of A1 in oligodendrogliogenesis and its relevance for myelination. PMID:25662897

  13. Entrapment in anti myelin-associated glycoprotein neuropathy.

    PubMed

    Faber, Catharina G; Notermans, Nicolette C; Wokke, John H J; Franssen, Hessel

    2009-04-01

    Anti-myelin associated glycoprotein (MAG) neuropathy is a chronic disorder in which IgM antibodies react with Schwann cell glycoproteins, including MAG and peripheral myelin protein 22 (PMP22). Nerve conduction studies show features of axon loss and predominantly distal slowing consistent with demyelination. Because a genetic loss of PMP22 function yields hereditary neuropathy with liability to pressure palsies (HNPP), loss of PMP22 function due to anti- MAG antibodies may result in increased sensitivity to entrapment. We investigated this by performing standardized electrophysiological studies in 16 patients with anti-MAG neuropathy and 16 disease controls with genetically confirmed HNPP. Disproportionate slowing relative to adjacent segments occurred in similar proportions of patients with anti-MAG neuropathy and HNPP, and was of the same magnitude in each group. Affected were the elbow, carpal tunnel and the wrist-hand segments of the median and ulnar nerves. However, in anti-MAG neuropathy as compared to HNPP, absolute values of distal motor latencies and conduction velocities outside entrapment sites were slower and amplitudes were lower. In conclusion, increased sensitivity for entrapment may occur in anti-MAG neuropathy and contribute to part of the nerve damage. PMID:19306083

  14. PTEN inhibitor bisperoxovanadium protects oligodendrocytes and myelin and prevents neuronal atrophy in adult rats following cervical hemicontusive spinal cord injury

    PubMed Central

    Walker, Chandler L.; Xu, Xiao-Ming

    2014-01-01

    Cervical spinal cord injury (SCI) damages axons and motor neurons responsible for ipsilateral forelimb function and causes demyelination and oligodendrocyte death. Inhibition of the phosphatase and tensin homologue, PTEN, promotes neural cell survival, neuroprotection and regeneration in vivo and in vitro. PTEN inhibition can also promote oligodendrocyte-mediated myelination of axons in vitro likely through Akt activation. We recently demonstrated that acute treatment with phosphatase PTEN inhibitor, bisperoxovanadium (bpV)-pic reduced tissue damage, neuron death, and promoted functional recovery after cervical hemi-contusion SCI. Evidence suggests bpV can promote myelin stability; however, bpV effects on myelination and oligodendrocytes in contusive SCI models are unclear. We hypothesized that bpV could increase myelin around the injury site through sparing or remyelination, and that bpV treatment may promote increased numbers of oligodendrocytes. Using histological and immunofluorescence labeling, we found that bpV treatment promoted significant spared white matter (30%; p < 0.01) and Luxol Fast Blue (LFB)+ myelin area rostral (Veh: 0.56 ± 0.01 vs. bpV: 0.64 ± 0.02; p < 0.05) and at the epicenter (Veh: 0.4175 ± 0.03 vs. bpV: 0.5400 ± 0.03; p < 0.05). VLF oligodendrocytes were also significantly greater with bpV therapy (109 ± 5.3 vs. Veh: 77 ± 2.7/mm2; p < 0.01). In addition, bpV increased mean motor neuron soma area versus vehicle-treatment (1.0 ± 0.02 vs. Veh: 0.77 ± 0.02) relative to Sham neuron size. This study provides key insight into additional cell and tissue effects that could contribute to bpV-mediated functional recovery observed after contusive cervical SCI. PMID:24582904

  15. GRASP: a novel heparin-binding serum glycoprotein that mediates oligodendrocyte-substratum adhesion.

    PubMed

    Schirmer, E C; Farooqui, J; Polak, P E; Szuchet, S

    1994-11-01

    Cell-substratum adhesion plays a crucial part in the cascade of events that control growth or turn on and consummate a differentiation program. We are investigating the molecular basis of oligodendrocyte (OLG) cytodifferentiation, employing pure cultures of OLGs isolated from postmyelination brains. We have shown that such OLGs will regenerate in vitro and reenact the ontogenic development of myelin, but to do so they need a signal. Adherence to a polylysine surface in the presence of 20% horse serum generates such a signal. Among the events that are turned on upon OLG adhesion is the phosphorylation of myelin basic protein; no such phosphorylation takes place in the non-adhered cell. We postulated that horse serum provides an adhesion molecule. Laminin, fibronectin, collagen and native vitronectin failed to replace horse serum. Hence, we set out to fractionate horse serum by screening with an adhesion assay. We report here the identification, purification and partial characterization of a novel, heparin-binding horse serum glycoprotein that we have termed Glycine-Rich Adhesion Serum Protein--GRASP--to stress the fact that this protein has a high content of glycine and functions, in vitro, as an adhesion molecule for OLGs. There is 61% similarity at the N-terminus between GRASP and histidine-rich glycoprotein precursor (HRGP), an alpha 2-glycoprotein from human plasma. However, our data suggest that GRASP is not the horse serum homolog of HRGP. First, the two Gps are functionally distinct: HRGP does not promote the adhesion of OLGs. Second, the amino acid compositions differ significantly, e.g., GRASP is not histidine- but rather glycine-rich. Third, the region of sequence similarity between GRASP and HRGP is conserved throughout the cystatin superfamily. Fourth, anti-Gp55 polyclonal Abs recognize a similar set of polypeptides--save for slight differences in M(r)-in human serum as in horse serum, indicating that HRGP and GRASP are two distinct but related proteins

  16. Myelin repair in vivo is increased by targeting oligodendrocyte precursor cells with nanoparticles encapsulating leukaemia inhibitory factor (LIF).

    PubMed

    Rittchen, Sonja; Boyd, Amanda; Burns, Alasdair; Park, Jason; Fahmy, Tarek M; Metcalfe, Su; Williams, Anna

    2015-07-01

    Multiple sclerosis (MS) is a progressive demyelinating disease of the central nervous system (CNS). Many nerve axons are insulated by a myelin sheath and their demyelination not only prevents saltatory electrical signal conduction along the axons but also removes their metabolic support leading to irreversible neurodegeneration, which currently is untreatable. There is much interest in potential therapeutics that promote remyelination and here we explore use of leukaemia inhibitory factor (LIF), a cytokine known to play a key regulatory role in self-tolerant immunity and recently identified as a pro-myelination factor. In this study, we tested a nanoparticle-based strategy for targeted delivery of LIF to oligodendrocyte precursor cells (OPC) to promote their differentiation into mature oligodendrocytes able to repair myelin. Poly(lactic-co-glycolic acid)-based nanoparticles of ∼120 nm diameter were constructed with LIF as cargo (LIF-NP) with surface antibodies against NG-2 chondroitin sulfate proteoglycan, expressed on OPC. In vitro, NG2-targeted LIF-NP bound to OPCs, activated pSTAT-3 signalling and induced OPC differentiation into mature oligodendrocytes. In vivo, using a model of focal CNS demyelination, we show that NG2-targeted LIF-NP increased myelin repair, both at the level of increased number of myelinated axons, and increased thickness of myelin per axon. Potency was high: a single NP dose delivering picomolar quantities of LIF is sufficient to increase remyelination. Impact statement Nanotherapy-based delivery of leukaemia inhibitory factor (LIF) directly to OPCs proved to be highly potent in promoting myelin repair in vivo: this delivery strategy introduces a novel approach to delivering drugs or biologics targeted to myelin repair in diseases such as MS. PMID:25934281

  17. Myelin repair in vivo is increased by targeting oligodendrocyte precursor cells with nanoparticles encapsulating leukaemia inhibitory factor (LIF)

    PubMed Central

    Rittchen, Sonja; Boyd, Amanda; Burns, Alasdair; Park, Jason; Fahmy, Tarek M.; Metcalfe, Su; Williams, Anna

    2015-01-01

    Multiple sclerosis (MS) is a progressive demyelinating disease of the central nervous system (CNS). Many nerve axons are insulated by a myelin sheath and their demyelination not only prevents saltatory electrical signal conduction along the axons but also removes their metabolic support leading to irreversible neurodegeneration, which currently is untreatable. There is much interest in potential therapeutics that promote remyelination and here we explore use of leukaemia inhibitory factor (LIF), a cytokine known to play a key regulatory role in self-tolerant immunity and recently identified as a pro-myelination factor. In this study, we tested a nanoparticle-based strategy for targeted delivery of LIF to oligodendrocyte precursor cells (OPC) to promote their differentiation into mature oligodendrocytes able to repair myelin. Poly(lactic-co-glycolic acid)-based nanoparticles of ∼120 nm diameter were constructed with LIF as cargo (LIF-NP) with surface antibodies against NG-2 chondroitin sulfate proteoglycan, expressed on OPC. In vitro, NG2-targeted LIF-NP bound to OPCs, activated pSTAT-3 signalling and induced OPC differentiation into mature oligodendrocytes. In vivo, using a model of focal CNS demyelination, we show that NG2-targeted LIF-NP increased myelin repair, both at the level of increased number of myelinated axons, and increased thickness of myelin per axon. Potency was high: a single NP dose delivering picomolar quantities of LIF is sufficient to increase remyelination. Impact statement Nanotherapy-based delivery of leukaemia inhibitory factor (LIF) directly to OPCs proved to be highly potent in promoting myelin repair in vivo: this delivery strategy introduces a novel approach to delivering drugs or biologics targeted to myelin repair in diseases such as MS. PMID:25934281

  18. Myelinating satellite oligodendrocytes are integrated in a glial syncytium constraining neuronal high-frequency activity

    PubMed Central

    Battefeld, Arne; Klooster, Jan; Kole, Maarten H. P.

    2016-01-01

    Satellite oligodendrocytes (s-OLs) are closely apposed to the soma of neocortical layer 5 pyramidal neurons but their properties and functional roles remain unresolved. Here we show that s-OLs form compact myelin and action potentials of the host neuron evoke precisely timed Ba2+-sensitive K+ inward rectifying (Kir) currents in the s-OL. Unexpectedly, the glial K+ inward current does not require oligodendrocytic Kir4.1. Action potential-evoked Kir currents are in part mediated by gap–junction coupling with neighbouring OLs and astrocytes that form a syncytium around the pyramidal cell body. Computational modelling predicts that glial Kir constrains the perisomatic [K+]o increase most importantly during high-frequency action potentials. Consistent with these predictions neurons with s-OLs showed a reduced probability for action potential burst firing during [K+]o elevations. These data suggest that s-OLs are integrated into a glial syncytium for the millisecond rapid K+ uptake limiting activity-dependent [K+]o increase in the perisomatic neuron domain. PMID:27161034

  19. Myelinating satellite oligodendrocytes are integrated in a glial syncytium constraining neuronal high-frequency activity.

    PubMed

    Battefeld, Arne; Klooster, Jan; Kole, Maarten H P

    2016-01-01

    Satellite oligodendrocytes (s-OLs) are closely apposed to the soma of neocortical layer 5 pyramidal neurons but their properties and functional roles remain unresolved. Here we show that s-OLs form compact myelin and action potentials of the host neuron evoke precisely timed Ba(2+)-sensitive K(+) inward rectifying (Kir) currents in the s-OL. Unexpectedly, the glial K(+) inward current does not require oligodendrocytic Kir4.1. Action potential-evoked Kir currents are in part mediated by gap-junction coupling with neighbouring OLs and astrocytes that form a syncytium around the pyramidal cell body. Computational modelling predicts that glial Kir constrains the perisomatic [K(+)]o increase most importantly during high-frequency action potentials. Consistent with these predictions neurons with s-OLs showed a reduced probability for action potential burst firing during [K(+)]o elevations. These data suggest that s-OLs are integrated into a glial syncytium for the millisecond rapid K(+) uptake limiting activity-dependent [K(+)]o increase in the perisomatic neuron domain. PMID:27161034

  20. Human umbilical cord Wharton's jelly-derived oligodendrocyte precursor-like cells for axon and myelin sheath regeneration★

    PubMed Central

    Chen, Hong; Zhang, Yan; Yang, Zhijun; Zhang, Hongtian

    2013-01-01

    Human umbilical mesenchymal stem cells from Wharton's jelly of the umbilical cord were induced to differentiate into oligodendrocyte precursor-like cells in vitro. Oligodendrocyte precursor cells were transplanted into contused rat spinal cords. Immunofluorescence double staining indicated that transplanted cells survived in injured spinal cord, and differentiated into mature and immature oligodendrocyte precursor cells. Biotinylated dextran amine tracing results showed that cell transplantation promoted a higher density of the corticospinal tract in the central and caudal parts of the injured spinal cord. Luxol fast blue and toluidine blue staining showed that the volume of residual myelin was significantly increased at 1 and 2 mm rostral and caudal to the lesion epicenter after cell transplantation. Furthermore, immunofluorescence staining verified that the newly regenerated myelin sheath was derived from the central nervous system. Basso, Beattie and Bresnahan testing showed an evident behavioral recovery. These results suggest that human umbilical mesenchymal stem cell-derived oligodendrocyte precursor cells promote the regeneration of spinal axons and myelin sheaths. PMID:25206380

  1. Differential roles of astrocyte and microglia in supporting oligodendrocyte development and myelination in vitro

    PubMed Central

    Pang, Yi; Fan, Lir-Wan; Tien, Lu-Tai; Dai, XueMei; Zheng, Baoying; Cai, Zhengwei; Lin, Rick C S; Bhatt, Abhay

    2013-01-01

    Oligodendrocyte (OL) development relies on many extracellular cues, most of which are secreted cytokines from neighboring neural cells. Although it is generally accepted that both astrocytes and microglia are beneficial for OL development, there is a lack of understanding regarding whether astrocytes and microglia play similar or distinct roles. The current study examined the effects of astrocytes and microglia on OL developmental phenotypes including cell survival, proliferation, differentiation, and myelination in vitro. Our data reveal that, although both astrocytes- and microglia-conditioned medium (ACDM and MCDM, respectively) protect OL progenitor cells (OPCs) against growth factor withdrawal-induced apoptosis, ACDM is significantly more effective than MCDM in supporting long-term OL survival. In contrast, MCDM preferentially promotes OL differentiation and myelination. These differential effects of ACDM and MCDM on OL development are highlighted by distinct pattern of cytokine/growth factors in the conditioned medium, which correlates with differentially activated intracellular signaling pathways in OPCs upon exposure to the conditioned medium. PMID:24392271

  2. Kif1b is essential for mRNA localization in oligodendrocytes and development of myelinated axons

    PubMed Central

    Lyons, David A.; Naylor, Stephen G.; Scholze, Anja; Talbot, William S.

    2009-01-01

    The kinesin motor protein Kif1b has previously been implicated in the axonal transport of mitochondria and synaptic vesicles1,2. More recently kif1b has been linked with susceptibility to Multiple Sclerosis (MS) 3. Here we show that Kif1b is required for the localization of myelin basic protein mRNA to processes of myelinating oligodendrocytes in zebrafish. We observe the ectopic appearance of myelin-like membrane in kif1b mutants, coincident with the ectopic localization of myelin proteins in kif1b mutant oligodendrocyte cell bodies. These observations suggest the hypothesis that oligodendrocytes localize certain mRNA molecules, namely those encoding small basic proteins such as mbp, to prevent aberrant effects of these proteins elsewhere in the cell. We also find that Kif1b is required for outgrowth of some of the longest axons in the peripheral and central nervous systems. Our data demonstrate new functions of kif1b in vivo and provide insights into its possible roles in Multiple Sclerosis. PMID:19503091

  3. Oligodendrocyte Morphometry and Expression of Myelin – Related mRNA in Ventral Prefrontal White Matter in Major Depressive Disorder

    PubMed Central

    Rajkowska, Grazyna; Mahajan, Gouri; Maciag, Dorota; Sathyanesan, Monica; Iyo, Abiye H.; Moulana, Mohadetheh; Kyle, Patrick B.; Woolverton, William L.; Miguel-Hidalgo, Jose Javier; Stockmeier, Craig A.; Newton, Samuel S.

    2015-01-01

    White matter disturbance in the ventral prefrontal cortex (vPFC) in major depressive disorder (MDD) has been noted with diffusion tensor imaging (DTI). However, the cellular and molecular pathology of prefrontal white matter in MDD and potential influence of antidepressant medications is not fully understood. Oligodendrocyte morphometry and myelin-related mRNA and protein expression was examined in the white matter of the vPFC in MDD. Sections of deep and gyral white matter from the vPFC were collected from 20 subjects with MDD and 16 control subjects. Density and size of CNPase-immunoreactive (−IR) oligodendrocytes were estimated using 3-dimensional cell counting. While neither density nor soma size of oligodendrocytes was significantly affected in deep white matter, soma size was significantly decreased in the gyral white matter in MDD. In rhesus monkeys treated chronically with fluoxetine there was no significant effect on oligodendrocyte morphometry. Using quantitative RTPCR to measure oligodendrocyte-related mRNA for CNPase, PLP1, MBP, MOG, MOBP, Olig1 and Olig2, in MDD there was a significantly reduced expression of PLP1 mRNA (which positively correlated with smaller sizes) and increased expression of mRNA for CNPase, OLIG1 and MOG. The expression of CNPase protein was significantly decreased in MDD. Altered expression of four myelin genes and CNPase protein suggests a mechanism for the degeneration of cortical axons and dysfunctional maturation of oligodendrocytes in MDD. The change in oligodendrocyte morphology in gyral white matter may parallel altered axonal integrity as revealed by DTI. PMID:25930075

  4. How big is the myelinating orchestra? Cellular diversity within the oligodendrocyte lineage: facts and hypotheses

    PubMed Central

    Tomassy, Giulio Srubek; Fossati, Valentina

    2014-01-01

    Since monumental studies from scientists like His, Ramón y Cajal, Lorente de Nó and many others have put down roots for modern neuroscience, the scientific community has spent a considerable amount of time, and money, investigating any possible aspect of the evolution, development and function of neurons. Today, the complexity and diversity of myriads of neuronal populations, and their progenitors, is still focus of extensive studies in hundreds of laboratories around the world. However, our prevalent neuron-centric perspective has dampened the efforts in understanding glial cells, even though their active participation in the brain physiology and pathophysiology has been increasingly recognized over the years. Among all glial cells of the central nervous system (CNS), oligodendrocytes (OLs) are a particularly specialized type of cells that provide fundamental support to neuronal activity by producing the myelin sheath. Despite their functional relevance, the developmental mechanisms regulating the generation of OLs are still poorly understood. In particular, it is still not known whether these cells share the same degree of heterogeneity of their neuronal companions and whether multiple subtypes exist within the lineage. Here, we will review and discuss current knowledge about OL development and function in the brain and spinal cord. We will try to address some specific questions: do multiple OL subtypes exist in the CNS? What is the evidence for their existence and those against them? What are the functional features that define an oligodendrocyte? We will end our journey by reviewing recent advances in human pluripotent stem cell differentiation towards OLs. This exciting field is still at its earliest days, but it is quickly evolving with improved protocols to generate functional OLs from different spatial origins. As stem cells constitute now an unprecedented source of human OLs, we believe that they will become an increasingly valuable tool for deciphering

  5. Oligodendrocyte Precursor Cell-Intrinsic Effect of Rheb1 Controls Differentiation and Mediates mTORC1-Dependent Myelination in Brain

    PubMed Central

    Zou, Yi; Jiang, Wanxiang; Wang, Jianqing; Li, Zhongping; Zhang, Junyan; Bu, Jicheng; Zou, Jia; Zhou, Liang; Yu, Shouyang; Cui, Yiyuan; Yang, Weiwei; Luo, Liping; Lu, Qing R.; Liu, Yanhui; Chen, Mina

    2014-01-01

    Rheb1 is an immediate early gene that functions to activate mammalian target of rapamycin (mTor) selectively in complex 1 (mTORC1). We have demonstrated previously that Rheb1 is essential for myelination in the CNS using a Nestin-Cre driver line that deletes Rheb1 in all neural cell lineages, and recent studies using oligodendrocyte-specific CNP-Cre have suggested a preferential role for mTORC1 is myelination in the spinal cord. Here, we examine the role of Rheb1/mTORC1 in mouse oligodendrocyte lineage using separate Cre drivers for oligodendrocyte progenitor cells (OPCs) including Olig1-Cre and Olig2-Cre as well as differentiated and mature oligodendrocytes including CNP-Cre and Tmem10-Cre. Deletion of Rheb1 in OPCs impairs their differentiation to mature oligodendrocytes. This is accompanied by reduced OPC cell-cycle exit suggesting a requirement for Rheb1 in OPC differentiation. The effect of Rheb1 on OPC differentiation is mediated by mTor since Olig1-Cre deletion of mTor phenocopies Olig1-Cre Rheb1 deletion. Deletion of Rheb1 in mature oligodendrocytes, in contrast, does not disrupt developmental myelination or myelin maintenance. Loss of Rheb1 in OPCs or neural progenitors does not affect astrocyte formation in gray and white matter, as indicated by the pan-astrocyte marker Aldh1L1. We conclude that OPC-intrinsic mTORC1 activity mediated by Rheb1 is critical for differentiation of OPCs to mature oligodendrocytes, but that mature oligodendrocytes do not require Rheb1 to make myelin or maintain it in the adult brain. These studies reveal mechanisms that may be relevant for both developmental myelination and impaired remyelination in myelin disease. PMID:25411504

  6. Antibodies to myelin-associated glycoprotein accelerate preferential motor reinnervation.

    PubMed

    Mears, Simon; Schachner, Melitta; Brushart, Thomas M

    2003-06-01

    Predegeneration of nerve enhances its ability to support axon regeneration. Trophic factors are upregulated by reactive Schwann cells while potentially inhibitory molecules are removed. These experiments isolate the effects of one such inhibitory molecule, the myelin-associated glycoprotein (MAG), to determine its role in modifying regeneration after nerve repair. Suture of the mouse femoral nerve was followed by daily intraperitoneal injection of antibodies to MAG, antibodies to HNK-1, a specific muscle pathway marker, or no further treatment. Regeneration was assayed by double-labeling the femoral cutaneous and muscle branches with horseradish peroxidase and fluoro-gold after 4 weeks or 6 weeks of regeneration. Four weeks after nerve repair, selective reinnervation of the muscle branch by motoneurons, or preferential motor reinnervation (PMR), was not seen in either controls or L2-antibody-treated animals. In contrast, treatment with MAG antibodies resulted in dramatic PMR. By 6 weeks, the controls had achieved borderline specificity, substantial PMR developed in the L2 antibody group and the MAG group changed little. Blocking access to MAG in the distal nerve stump thus accelerated and enhanced PMR. Sensory regeneration was depressed by both antibody treatments at 4 weeks but recovered by 6 weeks. Antibody administration has a generalized effect on sensory regeneration that is unrelated to the behavior of motoneurons in the same nerve. PMID:12795713

  7. Effects of pronase and neuraminidase treatment on a myelin-associated glycoprotein in developing brain.

    PubMed Central

    Quarles, R H

    1976-01-01

    Rats (14 days old) were injected with [14c]fucose and young adult rats with [3H]fucose in order to label the myelin-associated glycoproteins. As previously reported, the major [14C]fucose-labelled glycoprotein in the immature myelin had a higher apparent molecular weight on sodium dodecyl sulphate/polyacrylamide gels that the [3H]fucose-labelled glycoprotein in mature myelin. This predominant doubly labelled glycoprotein component was partially purified by preparative gel electrophoresis and converted to glycopeptides by extensive Pronase digestion. Gel filtration on Sephadex G-50 separated the glycopeptides into several clases, which were designted A,B, C AND D, from high to low molecular weight. The 14C-labelled glycopeptides from immature myeline were enriched in the highest-molecular-weight class A relative to the 3H-labelled glycopeptides from mature myelin. Neuraminidase treatment of the glycoprotein before Pronase digestion greatly decreased the proportion of glycopeptides fractionating in the higher-molecular-weight classes and largely eliminated the developmental differences that were apparent by gel filtration. However, neuraminidase treatment did not decrease the magnitude of the developmental difference revealed by electrophoresing the intact glycoprotein on sodium dodecyl sulphate gels, although it did decrease the apparent molecular weight of the glycoprotein from both the 15-day-old and adult rats by an amount comparable in magnitude to that developmental difference. The results from gel filtration of glycopeptides indicate that there is a higher content of large molecular weight, sialic acid-rich oligosaccharide units in the glycoprotein of immature myelin. However, the higher apparent molecular weight for the glycoprotein from 15-day-old rats on sodium dodcyl sulphate gels is not due primarily to its higher sialic acid content. PMID:942396

  8. Nf1 Loss and Ras Hyperactivation in Oligodendrocytes Induce NOS-Driven Defects in Myelin and Vasculature

    PubMed Central

    Mayes, Debra A.; Rizvi, Tilat A.; Titus-Mitchell, Haley; Oberst, Rachel; Ciraolo, Georgianne M.; Vorhees, Charles V.; Robinson, Andrew P.; Miller, Stephen D.; Cancelas, Jose A.; Stemmer-Rachamimov, Anat O.; Ratner, Nancy

    2014-01-01

    SUMMARY Patients with neurofibromatosis type 1 (NF1) and Costello syndrome Rasopathy have behavioral deficits. In NF1 patients, these may correlate with white matter enlargement and aberrant myelin. To model these features, we induced Nf1 loss or HRas hyperactivation in mouse oligodendrocytes. Enlarged brain white matter tracts correlated with myelin decompaction, downregulation of claudin-11, and mislocalization of connexin-32. Surprisingly, non-cell-autonomous defects in perivascular astrocytes and the blood-brain barrier (BBB) developed, implicating a soluble mediator. Nitric oxide (NO) can disrupt tight junctions and gap junctions, and NO and NO synthases (NOS1–NOS3) were upregulated in mutant white matter. Treating mice with the NOS inhibitor NG-nitro-L-arginine methyl ester or the antioxidant N-acetyl cysteine corrected cellular phenotypes. CNP-HRasG12V mice also displayed locomotor hyperactivity, which could be rescued by antioxidant treatment. We conclude that Nf1/Ras regulates oligodendrocyte NOS and that dysregulated NO signaling in oligodendrocytes can alter the surrounding vasculature. The data suggest that anti-oxidants may improve some behavioral deficits in Rasopathy patients. PMID:24035394

  9. Regulation of PERK–eIF2α signalling by tuberous sclerosis complex-1 controls homoeostasis and survival of myelinating oligodendrocytes

    PubMed Central

    Jiang, Minqing; Liu, Lei; He, Xuelian; Wang, Haibo; Lin, Wensheng; Wang, Huimin; Yoon, Sung O.; Wood, Teresa L.; Lu, Q. Richard

    2016-01-01

    Tuberous sclerosis complex-1 or 2 (TSC1/2) mutations cause white matter abnormalities, including myelin deficits in the CNS; however, underlying mechanisms are not fully understood. TSC1/2 negatively regulate the function of mTOR, which is required for oligodendrocyte differentiation. Here we report that, unexpectedly, constitutive activation of mTOR signalling by Tsc1 deletion in the oligodendrocyte lineage results in severe myelination defects and oligodendrocyte cell death in mice, despite an initial increase of oligodendrocyte precursors during early development. Expression profiling analysis reveals that Tsc1 ablation induces prominent endoplasmic reticulum (ER) stress responses by activating a PERK–eIF2α signalling axis and Fas–JNK apoptotic pathways. Enhancement of the phospho-eIF2α adaptation pathway by inhibition of Gadd34-PP1 phosphatase with guanabenz protects oligodendrocytes and partially rescues myelination defects in Tsc1 mutants. Thus, TSC1-mTOR signalling acts as an important checkpoint for maintaining oligodendrocyte homoeostasis, pointing to a previously uncharacterized ER stress mechanism that contributes to hypomyelination in tuberous sclerosis. PMID:27416896

  10. Regulation of PERK-eIF2α signalling by tuberous sclerosis complex-1 controls homoeostasis and survival of myelinating oligodendrocytes.

    PubMed

    Jiang, Minqing; Liu, Lei; He, Xuelian; Wang, Haibo; Lin, Wensheng; Wang, Huimin; Yoon, Sung O; Wood, Teresa L; Lu, Q Richard

    2016-01-01

    Tuberous sclerosis complex-1 or 2 (TSC1/2) mutations cause white matter abnormalities, including myelin deficits in the CNS; however, underlying mechanisms are not fully understood. TSC1/2 negatively regulate the function of mTOR, which is required for oligodendrocyte differentiation. Here we report that, unexpectedly, constitutive activation of mTOR signalling by Tsc1 deletion in the oligodendrocyte lineage results in severe myelination defects and oligodendrocyte cell death in mice, despite an initial increase of oligodendrocyte precursors during early development. Expression profiling analysis reveals that Tsc1 ablation induces prominent endoplasmic reticulum (ER) stress responses by activating a PERK-eIF2α signalling axis and Fas-JNK apoptotic pathways. Enhancement of the phospho-eIF2α adaptation pathway by inhibition of Gadd34-PP1 phosphatase with guanabenz protects oligodendrocytes and partially rescues myelination defects in Tsc1 mutants. Thus, TSC1-mTOR signalling acts as an important checkpoint for maintaining oligodendrocyte homoeostasis, pointing to a previously uncharacterized ER stress mechanism that contributes to hypomyelination in tuberous sclerosis. PMID:27416896

  11. Essential role of B-Raf in oligodendrocyte maturation and myelination during postnatal central nervous system development

    PubMed Central

    Galabova-Kovacs, Gergana; Catalanotti, Federica; Matzen, Dana; Reyes, Gloria X.; Zezula, Jürgen; Herbst, Ruth; Silva, Alcino; Walter, Ingrid; Baccarini, Manuela

    2008-01-01

    Mutations in the extracellular signal-regulated kinase (ERK) pathway, particularly in the mitogen-activated protein kinase/ERK kinase (MEK) activator B-Raf, are associated with human tumorigenesis and genetic disorders. Hence, B-Raf is a prime target for molecule-based therapies, and understanding its essential biological functions is crucial for their success. B-Raf is expressed preferentially in cells of neuronal origin. Here, we show that in mice, conditional ablation of B-Raf in neuronal precursors leads to severe dysmyelination, defective oligodendrocyte differentiation, and reduced ERK activation in brain. Both B-Raf ablation and chemical inhibition of MEK impair oligodendrocyte differentiation in vitro. In glial cell cultures, we find B-Raf in a complex with MEK, Raf-1, and kinase suppressor of Ras. In B-Raf–deficient cells, more Raf-1 is recruited to MEK, yet MEK/ERK phosphorylation is impaired. These data define B-Raf as the rate-limiting MEK/ERK activator in oligodendrocyte differentiation and myelination and have implications for the design and use of Raf inhibitors. PMID:18332218

  12. Interaction of myelin basic protein with cytoskeletal and signaling proteins in cultured primary oligodendrocytes and N19 oligodendroglial cells

    PubMed Central

    2014-01-01

    Background The classic myelin basic protein (MBP) isoforms are intrinsically-disordered proteins of 14–21.5 kDa in size arising from the Golli (Gene in the Oligodendrocyte Lineage) gene complex, and are responsible for formation of the multilayered myelin sheath in the central nervous system. The predominant membrane-associated isoform of MBP is not simply a structural component of compact myelin but is highly post-translationally modified and multi-functional, having interactions with numerous proteins such as Ca2+-calmodulin, and with actin, tubulin, and proteins with SH3-domains, which it can tether to a lipid membrane in vitro. It co-localizes with such proteins in primary oligodendrocytes (OLGs) and in early developmental N19-OLGs transfected with fluorescently-tagged MBP. Results To provide further evidence for MBP associations with these proteins in vivo, we show here that MBP isoforms are co-immunoprecipitated from detergent extracts of primary OLGs together with actin, tubulin, zonula occludens 1 (ZO-1), cortactin, and Fyn kinase. We also carry out live-cell imaging of N19-OLGs co-transfected with fluorescent MBP and actin, and show that when actin filaments re-assemble after recovery from cytochalasin D treatment, MBP and actin are rapidly enriched and co-localized at certain sites at the plasma membrane and in newly-formed membrane ruffles. The MBP and actin distributions change similarly with time, suggesting a specific and dynamic association. Conclusions These results provide more direct evidence for association of the predominant 18.5-kDa MBP isoform with these proteins in primary OLGs and in live cells than previously could be inferred from co-localization observations. This study supports further a role for classic MBP isoforms in protein-protein interactions during membrane and cytoskeletal extension and remodeling in OLGs. PMID:24956930

  13. Differential regulation of oligodendrocyte markers by glucocorticoids: Post-transcriptional regulation of both proteolipid protein and myelin basic protein and transcriptional regulation of glycerol phosphate dehydrogenase

    SciTech Connect

    Kumar, S.; Cole, R.; Chiappelli, F.; De Vellis, J. )

    1989-09-01

    During neonatal development glucocorticoids potentiate oligodendrocyte differentiation and myelinogenesis by regulating the expression of myelin basic protein, proteolipid protein, and glycerol phosphate dehydrogenase. The actual locus at which hydrocortisone exerts its developmental influence on glial physiology is, however, not well understood. Gycerol phosphate dehydrogenase is glucocorticoid-inducible in oligodendrocytes at all stages of development both in vivo and in vitro. In newborn rat cerebral cultures, between 9 and 15 days in vitro, a 2- to 3-fold increase in myelin basic protein and proteolipid protein mRNA levels occurs in oligodendrocytes within 12 hr of hydrocortisone treatment. Immunostaining demonstrates that this increase in mRNAs is followed by a 2- to 3-fold increase in the protein levels within 24 hr. In vitro transcription assays performed with oligodendrocyte nuclei show an 11-fold increase in the transcriptional activity of glycerol phosphate dehydrogenase in response to hydrocortisone but no increase in transcription of myelin basic protein or proteolipid protein. These results indicate that during early myelinogeneis, glucocorticoids influence the expression of key oligodendroglial markers by different processes: The expression of glycerol phosphate dehydrogenase is regulated at the transcriptional level, whereas the expression of myelin basic protein and proteolipid protein is modulated via a different, yet uncharacterized, mechanism involving post-transcriptional regulation.

  14. Connexin-47 and connexin-32 in gap junctions of oligodendrocyte somata, myelin sheaths, paranodal loops and Schmidt-Lanterman incisures: implications for ionic homeostasis and potassium siphoning.

    PubMed

    Kamasawa, N; Sik, A; Morita, M; Yasumura, T; Davidson, K G V; Nagy, J I; Rash, J E

    2005-01-01

    The subcellular distributions and co-associations of the gap junction-forming proteins connexin 47 and connexin 32 were investigated in oligodendrocytes of adult mouse and rat CNS. By confocal immunofluorescence light microscopy, abundant connexin 47 was co-localized with astrocytic connexin 43 on oligodendrocyte somata, and along myelinated fibers, whereas connexin 32 without connexin 47 was co-localized with contactin-associated protein (caspr) in paranodes. By thin-section transmission electron microscopy, connexin 47 immunolabeling was on the oligodendrocyte side of gap junctions between oligodendrocyte somata and astrocytes. By freeze-fracture replica immunogold labeling, large gap junctions between oligodendrocyte somata and astrocyte processes contained much more connexin 47 than connexin 32. Along surfaces of internodal myelin, connexin 47 was several times as abundant as connexin 32, and in the smallest gap junctions, often occurred without connexin 32. In contrast, connexin 32 was localized without connexin 47 in newly-described autologous gap junctions in Schmidt-Lanterman incisures and between paranodal loops bordering nodes of Ranvier. Thus, connexin 47 in adult rodent CNS is the most abundant connexin in most heterologous oligodendrocyte-to-astrocyte gap junctions, whereas connexin 32 is the predominant if not sole connexin in autologous ("reflexive") oligodendrocyte gap junctions. These results clarify the locations and connexin compositions of heterologous and autologous oligodendrocyte gap junctions, identify autologous gap junctions at paranodes as potential sites for modulating paranodal electrical properties, and reveal connexin 47-containing and connexin 32-containing gap junctions as conduits for long-distance intracellular and intercellular movement of ions and associated osmotic water. The autologous gap junctions may regulate paranodal electrical properties during saltatory conduction. Acting in series and in parallel, autologous and

  15. Binding partners for the myelin-associated glycoprotein of N2A neuroblastoma cells.

    PubMed

    Strenge, K; Schauer, R; Kelm, S

    1999-02-01

    The myelin-associated glycoprotein (MAG) has been proposed to be important for the integrity of myelinated axons. For a better understanding of the interactions involved in the binding of MAG to neuronal axons, we performed this study to identify the binding partners for MAG on neuronal cells. Experiments with glycosylation inhibitors revealed that sialylated N-glycans of glycoproteins represent the major binding sites for MAG on the neuroblastoma cell line N2A. From extracts of [3H]glucosamine-labelled N2A cells several glycoproteins with molecular weights between 20 and 230 kDa were affinity-precipitated using immobilised MAG. The interactions of these proteins with MAG were sialic acid-dependent and specific for MAG. PMID:10037148

  16. Myelin-associated glycoprotein gene mutation causes Pelizaeus-Merzbacher disease-like disorder.

    PubMed

    Lossos, Alexander; Elazar, Nimrod; Lerer, Israela; Schueler-Furman, Ora; Fellig, Yakov; Glick, Benjamin; Zimmerman, Bat-El; Azulay, Haim; Dotan, Shlomo; Goldberg, Sharon; Gomori, John M; Ponger, Penina; Newman, J P; Marreed, Hodaifah; Steck, Andreas J; Schaeren-Wiemers, Nicole; Mor, Nofar; Harel, Michal; Geiger, Tamar; Eshed-Eisenbach, Yael; Meiner, Vardiella; Peles, Elior

    2015-09-01

    Pelizaeus-Merzbacher disease is an X-linked hypomyelinating leukodystrophy caused by mutations or rearrangements in PLP1. It presents in infancy with nystagmus, jerky head movements, hypotonia and developmental delay evolving into spastic tetraplegia with optic atrophy and variable movement disorders. A clinically similar phenotype caused by recessive mutations in GJC2 is known as Pelizaeus-Merzbacher-like disease. Both genes encode proteins associated with myelin. We describe three siblings of a consanguineous family manifesting the typical infantile-onset Pelizaeus-Merzbacher disease-like phenotype slowly evolving into a form of complicated hereditary spastic paraplegia with mental retardation, dysarthria, optic atrophy and peripheral neuropathy in adulthood. Magnetic resonance imaging and spectroscopy were consistent with a demyelinating leukodystrophy. Using genetic linkage and exome sequencing, we identified a homozygous missense c.399C>G; p.S133R mutation in MAG. This gene, previously associated with hereditary spastic paraplegia, encodes myelin-associated glycoprotein, which is involved in myelin maintenance and glia-axon interaction. This mutation is predicted to destabilize the protein and affect its tertiary structure. Examination of the sural nerve biopsy sample obtained in childhood in the oldest sibling revealed complete absence of myelin-associated glycoprotein accompanied by ill-formed onion-bulb structures and a relatively thin myelin sheath of the affected axons. Immunofluorescence, cell surface labelling, biochemical analysis and mass spectrometry-based proteomics studies in a variety of cell types demonstrated a devastating effect of the mutation on post-translational processing, steady state expression and subcellular localization of myelin-associated glycoprotein. In contrast to the wild-type protein, the p.S133R mutant was retained in the endoplasmic reticulum and was subjected to endoplasmic reticulum-associated protein degradation by the

  17. Fibronectin is a binding partner for the myelin-associated glycoprotein (siglec-4a).

    PubMed

    Strenge, K; Brossmer, R; Ihrig, P; Schauer, R; Kelm, S

    2001-06-22

    The myelin-associated glycoprotein (MAG) mediates cell-cell interactions between myelinating glial cells and neurons. Here we describe the extracellular matrix glycoprotein fibronectin as a binding partner of MAG. It has been identified by affinity precipitation with MAG-Fc from NG108-15 cells and by microsequencing of two peptides derived from a 210-kDa protein band. Western blot analysis showed that fibronectin is also present in MAG binding partners isolated from N(2)A (murine neuroblastoma) cells, rat brain and rat spinal cord. Different fibronectin isoforms have been isolated from brains of young and adult rats, indicating that the expression of MAG binding fibronectin changes during development. PMID:11423128

  18. Association and release of the major intrinsic membrane glycoprotein from peripheral nerve myelin.

    PubMed Central

    Poduslo, J F; Yao, J K

    1985-01-01

    Hypo-osmotic homogenization of the endoneurium from the adult-rat sciatic nerve and subsequent evaluation of the 197 000 g aqueous supernatant by sodium dodecyl sulphate pore-gradient electrophoresis (SDS-p.g.e.) revealed a release of the major glycoprotein (P0) (29 000 Mr) from peripheral nerve myelin. Immunological verification of the presence of this asparagine-linked glycoprotein in the aqueous supernatant was obtained by immune overlay after SDS-p.g.e. and electrophoretic transfer to nitrocellulose using anti-P0 gamma-globulin followed by autoradiographic detection with 125I-protein A. A comparison of successive hypo- and iso-osmotic extractions of the endoneurium revealed that the hypo-osmotic extraction released increasing amounts of P0 into the supernatant fraction, whereas the iso-osmotic treatment revealed lower levels of P0 extracted from the myelin and lesser amounts with each successive extraction. Three successive hypo-osmotic extractions resulted in a 2.0-, 2.9-, and 9.5-fold increase in the amount of P0 released compared with the successive iso-osmotic extractions. Although these results suggest that this major myelin glycoprotein has properties similar to those of extrinsic membrane proteins, temperature-dependent phase-partitioning experiments with Triton X-114 revealed that this glycoprotein is recovered in the detergent-enriched lower phase. These results indicate that this major myelin glycoprotein is an amphipathic integral membrane protein with a distinct hydrophobic domain and yet has solubility characteristics typical of an extrinsic membrane protein. P0 labelled in vitro with [3H]mannose could be immunoprecipitated from the aqueous supernatant with anti-P0 gamma-globulin by centrifugation at 197000g without the addition of second antibody or protein A. Analysis of such an immune precipitate after incorporation in vitro with [14C]acetate to label endoneurial lipids revealed that all major endoneurial lipid classes contained radioactive

  19. Expression of proteolipid protein gene in spinal cord stem cells and early oligodendrocyte progenitor cells is dispensable for normal cell migration and myelination.

    PubMed

    Harlow, Danielle E; Saul, Katherine E; Culp, Cecilia M; Vesely, Elisa M; Macklin, Wendy B

    2014-01-22

    Plp1 gene expression occurs very early in development, well before the onset of myelination, creating a conundrum with regard to the function of myelin proteolipid protein (PLP), one of the major proteins in compact myelin. Using PLP-EGFP mice to investigate Plp1 promoter activity, we found that, at very early time points, PLP-EGFP was expressed in Sox2+ undifferentiated precursors in the spinal cord ventricular zone (VZ), as well as in the progenitors of both neuronal and glial lineages. As development progressed, most PLP-EGFP-expressing cells gave rise to oligodendrocyte progenitor cells (OPCs). The expression of PLP-EGFP in the spinal cord was quite dynamic during development. PLP-EGFP was highly expressed as cells delaminated from the VZ. Expression was downregulated as cells moved laterally through the cord, and then robustly upregulated as OPCs differentiated into mature myelinating oligodendrocytes. The presence of PLP-EGFP expression in OPCs raises the question of its role in this migratory population. We crossed PLP-EGFP reporter mice into a Plp1-null background to investigate the role of PLP in early OPC development. In the absence of PLP, normal numbers of OPCs were generated and their distribution throughout the spinal cord was unaffected. However, the orientation and length of OPC processes during migration was abnormal in Plp1-null mice, suggesting that PLP plays a role either in the structural integrity of OPC processes or in their response to extracellular cues that orient process outgrowth. PMID:24453324

  20. Mice with conditional inactivation of fibroblast growth factor receptor-2 signaling in oligodendrocytes have normal myelin but display dramatic hyperactivity when combined with Cnp1 inactivation.

    PubMed

    Kaga, Y; Shoemaker, W J; Furusho, M; Bryant, M; Rosenbluth, J; Pfeiffer, S E; Oh, L; Rasband, M; Lappe-Siefke, C; Yu, K; Ornitz, D M; Nave, K-A; Bansal, R

    2006-11-22

    Fibroblast growth factor receptors (Fgfr) comprise a widely expressed family of developmental regulators implicated in oligodendrocyte (OL) maturation of the CNS. Fgfr2 is expressed by OLs in myelinated fiber tracks. In vitro, Fgfr2 is highly upregulated during OL terminal differentiation, and its activation leads to enhanced growth of OL processes and the formation of myelin-like membranes. To investigate the in vivo function of Fgfr2 signaling by myelinating glial cells, we inactivated the floxed Fgfr2 gene in mice that coexpress Cre recombinase (cre) as a knock-in gene into the OL-specific 2',3'-cyclic nucleotide phosphodiesterase (Cnp1) locus. Surprisingly, no obvious defects were detected in brain development of these conditional mutants, including the number of OLs, the onset and extent of myelination, the ultrastructure of myelin, and the expression level of myelin proteins. However, unexpectedly, a subset of these conditional Fgfr2 knock-out mice that are homozygous for cre and therefore are also Cnp1 null, displayed a dramatic hyperactive behavior starting at approximately 2 weeks of age. This hyperactivity was abolished by treatment with dopamine receptor antagonists or catecholamine biosynthesis inhibitors, suggesting that the symptoms involve a dysregulation of the dopaminergic system. Although the molecular mechanisms are presently unknown, this novel mouse model of hyperactivity demonstrates the potential involvement of OLs in neuropsychiatric disorders, as well as the nonpredictable role of genetic interactions in the behavioral phenotype of mice. PMID:17122059

  1. 2',3'-cyclic nucleotide 3'-phosphodiesterase, an oligodendrocyte-Schwann cell and myelin-associated enzyme of the nervous system.

    PubMed

    Sprinkle, T J

    1989-01-01

    2',3'-Cyclic nucleotide 3'-phosphohydrolase (E.C. 3.1.4.37; CNPase) is a myelin-associated enzyme. In central and peripheral nervous system tissues, the enzyme is localized almost exclusively in the two cell types that elaborate myelin, the oligodendrocyte and the Schwann cell, respectively. Nonneural sources of CNPase have also been described, but they all have much lower activities than those found in brain. The freshly isolated brain enzymes appear as closely spaced doublets at approximately 46 and 48 kDa on SDS-PAGE. The primary sequence appears highly conserved between these two proteins, designated CNP1 and CNP2. Major structural differences between these two proteins are most likely due to posttranslational modifications of the enzyme itself (certainly phosphorylation, possibly others) or to alternative splicing. The primary sequences of rat and bovine brain CNPase have now been deduced from the cDNA sequences and the enzymes appear to be unique. Current research suggests that CNPase is involved in the very rapid growth of myelin membrane during early oligodendrocyte membrane biogenesis and possibly maintenance. The absolute hydrolysis specificity, yielding 2'-mononucleotides from 2',3'-cyclic substrates, strongly suggests that CNPase is a nucleic acid enzyme, possibly related to RNA metabolism. PMID:2537684

  2. Role of IL-33 and ST2 signalling pathway in multiple sclerosis: expression by oligodendrocytes and inhibition of myelination in central nervous system.

    PubMed

    Allan, Debbie; Fairlie-Clarke, Karen J; Elliott, Christina; Schuh, Cornelia; Barnett, Susan C; Lassmann, Hans; Linnington, Christopher; Jiang, Hui-Rong

    2016-01-01

    Recent research findings have provided convincing evidence indicating a role for Interleukin-33 (IL-33) signalling pathway in a number of central nervous system (CNS) diseases including multiple sclerosis (MS) and Alzheimer's disease. However, the exact function of IL-33 molecule within the CNS under normal and pathological conditions is currently unknown. In this study, we have mapped cellular expression of IL-33 and its receptor ST2 by immunohistochemistry in the brain tissues of MS patients and appropriate controls; and investigated the functional significance of these findings in vitro using a myelinating culture system. Our results demonstrate that IL-33 is expressed by neurons, astrocytes and microglia as well as oligodendrocytes, while ST2 is expressed in the lesions by oligodendrocytes and within and around axons. Furthermore, the expression levels and patterns of IL-33 and ST2 in the lesions of acute and chronic MS patient brain samples are enhanced compared with the healthy brain tissues. Finally, our data using rat myelinating co-cultures suggest that IL-33 may play an important role in MS development by inhibiting CNS myelination. PMID:27455844

  3. Oligodendrocyte death results in immune-mediated CNS demyelination

    PubMed Central

    Traka, Maria; Podojil, Joseph R; McCarthy, Derrick P; Miller, Stephen D; Popko, Brian

    2016-01-01

    Although multiple sclerosis is a common neurological disorder, the origin of the autoimmune response against myelin, which is the characteristic feature of the disease, remains unclear. To investigate whether oligodendrocyte death could cause this autoimmune response, we examined the oligodendrocyte ablation Plp1-CreERT;ROSA26-eGFP-DTA (DTA) mouse model. Approximately 30 weeks after recovering from oligodendrocyte loss and demyelination, DTA mice develop a fatal secondary disease characterized by extensive myelin and axonal loss. Strikingly, late-onset disease was associated with increased numbers of T lymphocytes in the CNS and myelin oligodendrocyte glycoprotein (MOG)-specific T cells in lymphoid organs. Transfer of T cells derived from DTA mice to naive recipients resulted in neurological defects that correlated with CNS white matter inflammation. Furthermore, immune tolerization against MOG ameliorated symptoms. Overall, these data indicate that oligodendrocyte death is sufficient to trigger an adaptive autoimmune response against myelin, suggesting that a similar process can occur in the pathogenesis of multiple sclerosis. PMID:26656646

  4. Lysophosphatidic acid can support the formation of membranous structures and an increase in MBP mRNA levels in differentiating oligodendrocytes

    PubMed Central

    Nogaroli, Luciana; Yuelling, Larra M.; Dennis, Jameel; Gorse, Karen; Payne, Shawn G.; Fuss, Babette

    2009-01-01

    During development, differentiating oligodendrocytes progress in distinct maturation steps from premyelinating to myelinating cells. Such maturing oligodendrocytes express both receptors mediating signaling via extracellular lysophosphatidic acid (LPA) and the major enzyme generating extracellular LPA, namely phosphodiesterase-Iα/autotaxin (PD-Iα/ATX). However, the biological role of extracellular LPA during the maturation of differentiating oligodendrocytes is currently unclear. Here, we demonstrate that application of exogenous LPA induced an increase in the area occupied by the oligodendrocytes’ process network, but only when PD-Iα/ATX expression was down-regulated. This increase in network area was caused primarily by the formation of membranous structures. In addition, LPA increased the number of cells positive for myelin basic protein (MBP). This effect was associated by an increase in the mRNA levels coding for MBP but not myelin oligodendrocyte glycoprotein (MOG). Taken together, these data suggest that LPA may play a crucial role in regulating the later stages of oligodendrocyte maturation. PMID:18594965

  5. Glycan specificity of myelin-associated glycoprotein and sialoadhesin deduced from interactions with synthetic oligosaccharides.

    PubMed

    Strenge, K; Schauer, R; Bovin, N; Hasegawa, A; Ishida, H; Kiso, M; Kelm, S

    1998-12-01

    Myelin-associated glycoprotein (MAG) and sialoadhesin (Sn) bind to sialylated glycans on cell surfaces and are thought to be involved in cell-cell interactions. In order to investigate how the interactions of these proteins are influenced by the glycan structure, we compared the inhibitory potencies of different synthetic monovalent oligosaccharides and polyvalent polyacrylamide derivatives. Using oligosaccharides with modifications in the sialic acid, galactose or N-acetylglucosamine moieties, we could demonstrate that both MAG and Sn bind with high preference to alpha2,3-linked sialic acid and interact at least with the three terminal monosaccharide units. For MAG, contacts with even more distant monosaccharides are likely, since pentasaccharides are bound better than trisaccharides. Also, an additional sialic acid at position six of the third-terminal monosaccharide unit enhances binding to MAG, whereas it does not influence binding to Sn significantly. Modifications of the sialic acid glycerol side chain demonstrated that the hydroxy groups at positions 8 and 9 are required for binding to both proteins. Surprisingly, MAG binds 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid significantly better than N-acetylneuraminic acid, whereas Sn prefers the latter structure. These results indicate that the interactions of MAG and Sn are mainly with sialic acid and that additional contacts with the subterminal galactose and N-acetylglucosamine residues also contribute to the binding strength, although to a lesser degree. PMID:9874234

  6. Dynamics and mechanisms of CNS myelination.

    PubMed

    Bercury, Kathryn K; Macklin, Wendy B

    2015-02-23

    Vertebrate myelination is an evolutionary advancement essential for motor, sensory, and higher-order cognitive function. CNS myelin, a multilamellar differentiation of the oligodendrocyte plasma membrane, ensheaths axons to facilitate electrical conduction. Myelination is one of the most pivotal cell-cell interactions for normal brain development, involving extensive information exchange between differentiating oligodendrocytes and axons. The molecular mechanisms of myelination are discussed, along with new perspectives on oligodendrocyte plasticity and myelin remodeling of the developing and adult CNS. PMID:25710531

  7. Lysosomal delivery of the major myelin glycoprotein in the absence of myelin assembly: posttranslational regulation of the level of expression by Schwann cells

    SciTech Connect

    Brunden, K.R.; Poduslo, J.F.

    1987-03-01

    The major myelin protein, P0, has been shown to have decreased levels of expression and altered oligosaccharide processing after the disruption of Schwann cell-axon interaction. We show here that lysosomal degradation of the glycoprotein shortly after its synthesis accounts for much of its decreased expression in the permanently transected adult rat sciatic nerve, a denervated preparation where there is no axonal regeneration or myelin assembly. If (/sup 3/H)mannose incorporation into sciatic nerve endoneurial slices is examined in the presence of the lysosomotropic agent, NH/sub 4/Cl, a marked increase in the level of newly synthesized P0 is seen. Pulse-chase analysis of (/sup 3/H)mannose-labeled P0 in the presence of NH/sub 4/Cl indicates that this increase is a consequence of inhibition of P0 degradation that normally occurs 1-2 h after biosynthesis in the transected nerve. P0 degradation can also be inhibited if lysosomal function is disturbed by dilation of secondary lysosomes with L-methionine methyl ester. The addition of deoxymannonojirimycin or swainsonine (SW), inhibitors of oligosaccharide-processing mannosidases I and II, respectively, also results in a decrease in P0 degradation. This inhibition is presumably caused by a blockage of transport to the lysosomes due to altered processing of the glycoprotein, although the direct inhibition of lysosomal mannosidases cannot be excluded. In contrast to the transected nerve, addition of NH/sub 4/Cl or SW has no effect on P0 levels in the crushed nerve, where myelin assembly occurs. The delivery of P0 to the lysosomes of the transected nerve Schwann cells does not appear to be triggered by the mannose-6-phosphate transport system involved in acid hydrolase routing.

  8. Oligodendrocytes in a Nutshell

    PubMed Central

    Michalski, John-Paul; Kothary, Rashmi

    2015-01-01

    Oligodendrocytes are the myelinating cells of the central nervous system (CNS). While the phrase is oft repeated and holds true, the last few years have borne witness to radical change in our understanding of this unique cell type. Once considered static glue, oligodendrocytes are now seen as plastic and adaptive, capable of reacting to a changing CNS. This review is intended as a primer and guide, exploring how the past 5 years have fundamentally altered our appreciation of oligodendrocyte development and CNS myelination. PMID:26388730

  9. Linkage analysis of candidate myelin genes in familial multiple sclerosis.

    PubMed

    Seboun, E; Oksenberg, J R; Rombos, A; Usuku, K; Goodkin, D E; Lincoln, R R; Wong, M; Pham-Dinh, D; Boesplug-Tanguy, O; Carsique, R; Fitoussi, R; Gartioux, C; Reyes, C; Ribierre, F; Faure, S; Fizames, C; Gyapay, G; Weissenbach, J; Dautigny, A; Rimmler, J B; Garcia, M E; Pericak-Vance, M A; Haines, J L; Hauser, S L

    1999-09-01

    Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system. A complex genetic etiology is thought to underlie susceptibility to this disease. The present study was designed to analyze whether differences in genes that encode myelin proteins influence susceptibility to MS. We performed linkage analysis of MS to markers in chromosomal regions that include the genes encoding myelin basic protein (MBP), proteolipid protein (PLP), myelin-associated glycoprotein (MAG), oligodendrocyte myelin glycoprotein (OMGP), and myelin oligodendrocyte glycoprotein (MOG) in a well-characterized population of 65 multiplex MS families consisting of 399 total individuals, 169 affected with MS and 102 affected sibpairs. Physical mapping data permitted placement of MAG and PLP genes on the Genethon genetic map; all other genes were mapped on the Genethon genetic map by linkage analysis. For each gene, at least one marker within the gene and/or two tightly linked flanking markers were analyzed. Marker data analysis employed a combination of genetic trait model-dependent (parametric) and model-independent linkage methods. Results indicate that MAG, MBP, OMGP, and PLP genes do not have a significant genetic effect on susceptibility to MS in this population. As MOG resides within the MHC, a potential role of the MOG gene could not be excluded. PMID:10541588

  10. Modulation of Canonical Transient Receptor Potential Channel 1 in the Proliferation of Oligodendrocyte Precursor Cells by the Golli Products of the Myelin Basic Protein Gene

    PubMed Central

    Paez, PM; Fulton, D; Spreuer, V; Handley, V; Campagnoni, AT

    2011-01-01

    Golli proteins, products of the myelin basic protein gene, function as a new type of modulator of intracellular Ca++ levels in oligodendrocyte progenitor cells (OPCs). Because of this, they affect a number of Ca++ dependent functions such as OPC migration and process extension. To examine further the Ca++ channels regulated by golli, we studied the store operated Ca++ channels (SOCCs) in OPCs and acute brain slice preparations from golli-KO and golli-overexpressing mice. Our results showed that pharmacologically-induced Ca++ release from intracellular stores evoked a significant extracellular Ca++ entry after store depletion in OPCs. They also indicated that under these pharmacological conditions golli promoted activation of Ca++ influx by SOCCs in cultured OPCs as well as in tissue slices. The Canonical TRP (Transient Receptor Potential) family of Ca++ channels (TRPCs) has been postulated to be SOCC subunits in oligodendrocytes. Using a siRNA knock down approach, we provided direct evidence that TRPC1 is involved in store-operated Ca++ influx in OPCs, and that it is modulated by golli. Furthermore, our data indicated that golli is probably associated with TRPC1 at OPC processes. Additionally, we found that TRPC1 expression is essential for the effects of golli on OPC proliferation. In summary, our data indicate a key role for golli proteins in the regulation of TRPC mediated Ca++ influx, a finding that has profound consequences for the regulation of multiple biological processes in OPCs. More important, we have shown that extracellular Ca++ uptake through TRPC1 is an essential component in the mechanism of OPC proliferation. PMID:21389218

  11. Tetrameric assembly of full-sequence protein zero myelin glycoprotein by synchrotron x-ray scattering.

    PubMed Central

    Inouye, H; Tsuruta, H; Sedzik, J; Uyemura, K; Kirschner, D A

    1999-01-01

    Highly purified myelin P0 glycoprotein was solubilized to 1-8 mg/ml in 0.1% sodium dodecyl sulfate (SDS), and the solution structure of the P0 assembly was studied using synchrotron x-ray scattering. The full-length P0, which was isolated from bovine intradural roots, included both the extracellular and cytoplasmic domains of the molecule. At the higher concentrations (4, 6, and 8 mg/ml, respectively), an x-ray intensity maximum was observed at 316 A, 245 A, and 240 A Bragg spacing. Because the position of this intensity depended on P0 concentration, it is most likely due to interparticle interference. By contrast, the position of a second intensity maximum, which was at approximately 40 A Bragg spacing, was invariant with P0 concentration. This latter intensity was accounted for by monodispersed, 80 A-diameter particles that are composed of eight, approximately 30 A-diameter spheres. Chemical parameters suggest that the 80 A particles correspond to the size of a tetramer of P0 molecules. Therefore, the approximately 30 A spheres would correspond to the sizes of the extracellular and cytoplasmic domains for each of the P0 monomers. The invariance of the second intensity maximum with P0 concentration indicates that the structure of the 80 A-diameter, tetrameric particles is unaltered. According to the liquid model for interparticle interference from charged spheres, the 80 A-diameter particle has 10 negative surface charges which likely arise from negatively charged SDS molecules bound to the transmembrane domain of P0. This binding, however, apparently does not alter the tetrameric assembly of P0, suggesting that intermolecular interactions involving extracellular domains and cytoplasmic domains likely stabilize this assembly. Some of our results have been published in abstract form (Inouye, H., H. Tsuruta, D. A. Kirschner, J. Sedzik, and K. Uyemura. Abstracts of the 4th International School and Symposium on Synchrotron Radiation in Natural Science, June 15

  12. Ncx3 gene ablation impairs oligodendrocyte precursor response and increases susceptibility to experimental autoimmune encephalomyelitis.

    PubMed

    Casamassa, Antonella; La Rocca, Claudia; Sokolow, Sophie; Herchuelz, Andre; Matarese, Giuseppe; Annunziato, Lucio; Boscia, Francesca

    2016-07-01

    The Na(+) /Ca(2+) exchanger NCX3, recently identified as a myelin membrane component, is involved in the regulation of [Ca(2+) ]i during oligodendrocyte maturation. Here NCX3 involvement was studied in myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Western blotting and quantitative colocalization studies performed in wild-type ncx3(+/+) mice at different stages of EAE disease showed that NCX3 protein was intensely upregulated during the chronic stage, where it was intensely coexpressed with the oligodendrocyte precursor cells (OPC) marker NG2 and the premyelinating marker CNPase. Moreover, MOG35-55 -immunized mice lacking the ncx3 gene displayed not only a reduced diameter of axons and an intact myelin ring number but also a dramatic decrease in OPC and pre-myelinating cells in the white matter of the spinal cord when compared with ncx3(+/+) . Accordingly, ncx3(-/-) and ncx3(+/-) mutants developed early onset of EAE and more severe clinical symptoms. Interestingly, cytofluorimetric analysis revealed that during the peak stage of the disease, the number of immune T-cell subsets in ncx3(-/-) mice, was not statistically different from that measured in ncx3(+/+) . Our findings demonstrate that knocking-out NCX3 impairs oligodendrocyte response and worsens clinical symptoms in EAE without altering the immune T-cell population. GLIA 2016;64:1124-1137. PMID:27120265

  13. Identification of three microsatellites at the human myelin oligodendrocyte glycoprotein (MOG) locus, a gene potentially involved in multiple sclerosis

    SciTech Connect

    Borot, N.; Dolbois, L.; Coppin, H.

    1994-09-01

    The gene encoding MOG is located on the short arm of chromosome 6, less than 120 kb telomeric to HLA-F. We have cloned the MOG gene from a cosmid library. Using tandemly repeated dinucleotides, we probed the genomic region containing the human MOG gene in order to identify and localize polymorphic markers: three microsatellites were characterized in that region. Using a polymerase chain reaction-based technique, we studied length variability for these three markers among 173 healthy individuals and 167 multiple sclerosis patients. Heterozygosity varied from 50% to 60% according to the marker. Pairwise studies showed significant linkage disequilibrium between some alleles. Multiple sclerosis patients and controls were not shown to have statistically significant differences in the MOG region. Further studies on the coding regions are in progress in order to exclude any involvement of the MOG gene in multiple sclerosis.

  14. Myelin Proteolipid Protein Complexes with αv Integrin and AMPA Receptors In Vivo and Regulates AMPA-Dependent Oligodendrocyte Progenitor Cell Migration through the Modulation of Cell-Surface GluR2 Expression

    PubMed Central

    Harlow, Danielle E.; Saul, Katherine E.; Komuro, Hitoshi

    2015-01-01

    In previous studies, stimulation of ionotropic AMPA/kainate glutamate receptors on cultured oligodendrocyte cells induced the formation of a signaling complex that includes the AMPA receptor, integrins, calcium-binding proteins, and, surprisingly, the myelin proteolipid protein (PLP). AMPA stimulation of cultured oligodendrocyte progenitor cells (OPCs) also caused an increase in OPC migration. The current studies focused primarily on the formation of the PLP–αv integrin–AMPA receptor complex in vivo and whether complex formation impacts OPC migration in the brain. We found that in wild-type cerebellum, PLP associates with αv integrin and the calcium-impermeable GluR2 subunit of the AMPA receptor, but in mice lacking PLP, αv integrin did not associate with GluR2. Live imaging studies of OPC migration in ex vivo cerebellar slices demonstrated altered OPC migratory responses to neurotransmitter stimulation in the absence of PLP and GluR2 or when αv integrin levels were reduced. Chemotaxis assays of purified OPCs revealed that AMPA stimulation was neither attractive nor repulsive but clearly increased the migration rate of wild-type but not PLP null OPCs. AMPA receptor stimulation of wild-type OPCs caused decreased cell-surface expression of the GluR2 AMPA receptor subunit and increased intracellular Ca2+ signaling, whereas PLP null OPCs did not reduce GluR2 at the cell surface or increase Ca2+ signaling in response to AMPA treatment. Together, these studies demonstrate that PLP is critical for OPC responses to glutamate signaling and has important implications for OPC responses when levels of glutamate are high in the extracellular space, such as following demyelination. SIGNIFICANCE STATEMENT After demyelination, such as occurs in multiple sclerosis, remyelination of axons is often incomplete, leading to loss of neuronal function and clinical disability. Remyelination may fail because oligodendrocyte precursor cells (OPCs) do not completely migrate into

  15. How to make an oligodendrocyte.

    PubMed

    Goldman, Steven A; Kuypers, Nicholas J

    2015-12-01

    Oligodendrocytes produce myelin, an insulating sheath required for the saltatory conduction of electrical impulses along axons. Oligodendrocyte loss results in demyelination, which leads to impaired neurological function in a broad array of diseases ranging from pediatric leukodystrophies and cerebral palsy, to multiple sclerosis and white matter stroke. Accordingly, replacing lost oligodendrocytes, whether by transplanting oligodendrocyte progenitor cells (OPCs) or by mobilizing endogenous progenitors, holds great promise as a therapeutic strategy for the diseases of central white matter. In this Primer, we describe the molecular events regulating oligodendrocyte development and how our understanding of this process has led to the establishment of methods for producing OPCs and oligodendrocytes from embryonic stem cells and induced pluripotent stem cells, as well as directly from somatic cells. In addition, we will discuss the safety of engrafted stem cell-derived OPCs, as well as approaches by which to modulate their differentiation and myelinogenesis in vivo following transplantation. PMID:26628089

  16. The immunomodulatory oligodendrocyte.

    PubMed

    Zeis, Thomas; Enz, Lukas; Schaeren-Wiemers, Nicole

    2016-06-15

    Oligodendrocytes, the myelinating glial cells of the central nervous system (CNS), are due to their high specialization and metabolic needs highly vulnerable to various insults. This led to a general view that oligodendrocytes are defenseless victims during brain damage such as occurs in acute and chronic CNS inflammation. However, this view is challenged by increasing evidence that oligodendrocytes are capable of expressing a wide range of immunomodulatory molecules. They express various cytokines and chemokines (e.g. Il-1β, Il17A, CCL2, CXCL10), antigen presenting molecules (MHC class I and II) and co-stimulatory molecules (e.g. CD9, CD81), complement and complement receptor molecules (e.g. C1s, C2 and C3, C1R), complement regulatory molecules (e.g. CD46, CD55, CD59), tetraspanins (e.g. TSPAN2), neuroimmune regulatory proteins (e.g. CD200, CD47) as well as extracellular matrix proteins (e.g. VCAN) and many others. Their potential immunomodulatory properties can, at specific times and locations, influence ongoing immune processes as shown by numerous publications. Therefore, oligodendrocytes are well capable of immunomodulation, especially during the initiation or resolution of immune processes in which subtle signaling might tip the scale. A better understanding of the immunomodulatory oligodendrocyte can help to invent new, innovative therapeutic interventions in various diseases such as Multiple Sclerosis. This article is part of a Special Issue entitled SI: Myelin Evolution. PMID:26423932

  17. Accumulation of reactivity to MBP sensitizes TRAIL mediated oligodendrocyte apoptosis in adult sub cortical white matter in a model for human multiple sclerosis.

    PubMed

    Mir, Sajad; Ali, Farrah; Chauhan, Deepika; Arora, Rajesh; Khan, Haider A

    2016-04-01

    Reactivity to myelin associated proteins is the hallmark of human multiple sclerosis (M.S) and its experimental counterparts. However, the nature of such reactivity has not been described fully. Herein, we report that myelin basic protein (MBP) reactivity accumulates in a rat model for M.S. over a period of time and sensitizes TRAIL mediated progressive oligodendrocyte apoptosis. We used active immunization by Myelin Oligodendrocyte Glycoprotein (MOG, 50 μg) to study chronic remitting relapsing encephalomyelitis in rats. A time point analysis of the progressive disease revealed cumulative accumulation of anti myelin basic protein antibodies during the disease progression with minimal change in the anti-MOG antibodies. Increased reactivity to MBP was studied to sensitize TNF related apoptosis-inducing ligand (TRAIL) and other proinflammatory cytokines in a cumulative fashion leading to the Caspase dependent apoptosis of oligodendrocytes and myelin loss. In a rescue experiment, we could limit the demyelination and prevent disease progression by neutralizing the effector, TRAIL in an early stage of the disease. This is the first study to identify the accumulation of MBP antibodies in MOG induced EAE which possibly leads to TRAIL sensitized oligodendrocyte apoptosis in the white mater of EAE rats. This finding stresses on the need to study MBP antibody titers in M.S. patients and therefore might serve as an alternate marker for progressive demyelination. PMID:26477945

  18. Gangliosides are functional nerve cell ligands for myelin-associated glycoprotein (MAG), an inhibitor of nerve regeneration

    PubMed Central

    Vyas, Alka A.; Patel, Himatkumar V.; Fromholt, Susan E.; Heffer-Lauc, Marija; Vyas, Kavita A.; Dang, Jiyoung; Schachner, Melitta; Schnaar, Ronald L.

    2002-01-01

    Myelin-associated glycoprotein (MAG) binds to the nerve cell surface and inhibits nerve regeneration. The nerve cell surface ligand(s) for MAG are not established, although sialic acid-bearing glycans have been implicated. We identify the nerve cell surface gangliosides GD1a and GT1b as specific functional ligands for MAG-mediated inhibition of neurite outgrowth from primary rat cerebellar granule neurons. MAG-mediated neurite outgrowth inhibition is attenuated by (i) neuraminidase treatment of the neurons; (ii) blocking neuronal ganglioside biosynthesis; (iii) genetically modifying the terminal structures of nerve cell surface gangliosides; and (iv) adding highly specific IgG-class antiganglioside mAbs. Furthermore, neurite outgrowth inhibition is mimicked by highly multivalent clustering of GD1a or GT1b by using precomplexed antiganglioside Abs. These data implicate the nerve cell surface gangliosides GD1a and GT1b as functional MAG ligands and suggest that the first step in MAG inhibition is multivalent ganglioside clustering. PMID:12060784

  19. Nicotinic acetylcholine receptors mediate donepezil-induced oligodendrocyte differentiation.

    PubMed

    Imamura, Osamu; Arai, Masaaki; Dateki, Minori; Ogata, Toru; Uchida, Ryuji; Tomoda, Hiroshi; Takishima, Kunio

    2015-12-01

    Oligodendrocytes are the myelin-forming cells of the central nervous system (CNS). Failure of myelin development and oligodendrocyte loss results in serious human disorders, including multiple sclerosis. Here, we show that donepezil, an acetlycholinesterase inhibitor developed for the treatment of Alzheimer's disease, can stimulate oligodendrocyte differentiation and maturation of neural stem cell-derived oligodendrocyte progenitor cells without affecting proliferation or cell viability. Transcripts for essential myelin-associated genes, such as PLP, MAG, MBP, CNPase, and MOG, in addition to transcription factors that regulate oligodendrocyte differentiation and myelination, were rapidly increased after treatment with donepezil. Furthermore, luciferase assays confirmed that both MAG and MBP promoters display increased activity upon donepezil-induced oligodendrocytes differentiation, suggesting that donepezil increases myelin gene expression mainly through enhanced transcription. We also found that the increase in the number of oligodendrocytes observed following donepezil treatment was significantly inhibited by the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine, but not by the muscarinic acetylcholine receptor antagonist scopolamine. Moreover, donepezil-induced myelin-related gene expression was suppressed by mecamylamine at both the mRNA and protein level. These results suggest that donepezil stimulates oligodendrocyte differentiation and myelin-related gene expression via nAChRs in neural stem cell-derived oligodendrocyte progenitor cells. We show that donepezil, a drug for the treatment of Alzheimer disease, can stimulate oligodendrocyte differentiation and maturation of oligodendrocyte progenitor cells. Transcripts for essential myelin-associated genes, such as PLP, MAG, MBP, CNPase and MOG in addition to transcripton factors that regulate oligodendrocyte differentiation and myelination were rapidly increased after treatment with donepezil

  20. Recognition molecules myelin-associated glycoprotein and tenascin-C inhibit integrin-mediated adhesion of neural cells to collagen.

    PubMed

    Bachmann, M; Conscience, J F; Probstmeier, R; Carbonetto, S; Schachner, M

    1995-03-01

    Because of the importance of collagens in mediating cell-substrate interactions and the association of collagens with neural recognition molecules in the peripheral nervous system, the ability of neural recognition molecules to modify the substrate properties of collagens, in particular collagen type I, for cell adhesion was determined. Two cell lines, the N2A neuroblastoma and PC12 pheochromocytoma, were investigated for their capacity to adhere to different collagen types in the absence or presence of several neural recognition molecules. Adhesion of N2A or PC12 cells and membrane vesicles from PC12 cells to collagen type I was reduced when the collagen had been preincubated prior to its application as substrate with the extracellular domain of myelin-associated glycoprotein (s-MAG) or, as control, fibroblast tenascin-C (F-tenascin). In mixture with other collagen types, s-MAG was only able to reduce the adhesiveness of collagen types III and V, but not of collagen types II and IV. F-tenascin reduced the adhesiveness of all collagen types tested. In contrast to F-tenascin, s-MAG had to be present during fibrillogenesis to exert its effect, indicating that it must be coassembled into the collagen fibril to block the binding site. Cell adhesion to collagen type I was dependent on Mg2+ or Mn2+ and inhibited by a monoclonal antibody to the alpha 1 integrin subunit. The combined observations indicate that s-MAG and F-tenascin interfere with cell binding, most probably by modifying the integrin binding site, and that the two molecules act by different mechanisms, both leading to reduction of adhesion. PMID:7542351

  1. A critical role for the cholesterol-associated proteolipids PLP and M6B in myelination of the central nervous system.

    PubMed

    Werner, Hauke B; Krämer-Albers, Eva-Maria; Strenzke, Nicola; Saher, Gesine; Tenzer, Stefan; Ohno-Iwashita, Yoshiko; De Monasterio-Schrader, Patricia; Möbius, Wiebke; Moser, Tobias; Griffiths, Ian R; Nave, Klaus-Armin

    2013-04-01

    The formation of central nervous system myelin by oligodendrocytes requires sterol synthesis and is associated with a significant enrichment of cholesterol in the myelin membrane. However, it is unknown how oligodendrocytes concentrate cholesterol above the level found in nonmyelin membranes. Here, we demonstrate a critical role for proteolipids in cholesterol accumulation. Mice lacking the most abundant myelin protein, proteolipid protein (PLP), are fully myelinated, but PLP-deficient myelin exhibits a reduced cholesterol content. We therefore hypothesized that "high cholesterol" is not essential in the myelin sheath itself but is required for an earlier step of myelin biogenesis that is fully compensated for in the absence of PLP. We also found that a PLP-homolog, glycoprotein M6B, is a myelin component of low abundance. By targeting the Gpm6b-gene and crossbreeding, we found that single-mutant mice lacking either PLP or M6B are fully myelinated, while double mutants remain severely hypomyelinated, with enhanced neurodegeneration and premature death. As both PLP and M6B bind membrane cholesterol and associate with the same cholesterol-rich oligodendroglial membrane microdomains, we suggest a model in which proteolipids facilitate myelination by sequestering cholesterol. While either proteolipid can maintain a threshold level of cholesterol in the secretory pathway that allows myelin biogenesis, lack of both proteolipids results in a severe molecular imbalance of prospective myelin membrane. However, M6B is not efficiently sorted into mature myelin, in which it is 200-fold less abundant than PLP. Thus, only PLP contributes to the high cholesterol content of myelin by association and co-transport. PMID:23322581

  2. In vitro myelin formation using embryonic stem cells

    PubMed Central

    Kerman, Bilal E.; Kim, Hyung Joon; Padmanabhan, Krishnan; Mei, Arianna; Georges, Shereen; Joens, Matthew S.; Fitzpatrick, James A. J.; Jappelli, Roberto; Chandross, Karen J.; August, Paul; Gage, Fred H.

    2015-01-01

    Myelination in the central nervous system is the process by which oligodendrocytes form myelin sheaths around the axons of neurons. Myelination enables neurons to transmit information more quickly and more efficiently and allows for more complex brain functions; yet, remarkably, the underlying mechanism by which myelination occurs is still not fully understood. A reliable in vitro assay is essential to dissect oligodendrocyte and myelin biology. Hence, we developed a protocol to generate myelinating oligodendrocytes from mouse embryonic stem cells and established a myelin formation assay with embryonic stem cell-derived neurons in microfluidic devices. Myelin formation was quantified using a custom semi-automated method that is suitable for larger scale analysis. Finally, early myelination was followed in real time over several days and the results have led us to propose a new model for myelin formation. PMID:26015546

  3. α-Synuclein-induced myelination deficit defines a novel interventional target for multiple system atrophy.

    PubMed

    Ettle, Benjamin; Kerman, Bilal E; Valera, Elvira; Gillmann, Clarissa; Schlachetzki, Johannes C M; Reiprich, Simone; Büttner, Christian; Ekici, Arif B; Reis, André; Wegner, Michael; Bäuerle, Tobias; Riemenschneider, Markus J; Masliah, Eliezer; Gage, Fred H; Winkler, Jürgen

    2016-07-01

    Multiple system atrophy (MSA) is a rare atypical parkinsonian disorder characterized by a rapidly progressing clinical course and at present without any efficient therapy. Neuropathologically, myelin loss and neurodegeneration are associated with α-synuclein accumulation in oligodendrocytes, but underlying pathomechanisms are poorly understood. Here, we analyzed the impact of oligodendrocytic α-synuclein on the formation of myelin sheaths to define a potential interventional target for MSA. Post-mortem analyses of MSA patients and controls were performed to quantify myelin and oligodendrocyte numbers. As pre-clinical models, we used transgenic MSA mice, a myelinating stem cell-derived oligodendrocyte-neuron co-culture, and primary oligodendrocytes to determine functional consequences of oligodendrocytic α-synuclein overexpression on myelination. We detected myelin loss accompanied by preserved or even increased numbers of oligodendrocytes in post-mortem MSA brains or transgenic mouse forebrains, respectively, indicating an oligodendrocytic dysfunction in myelin formation. Corroborating this observation, overexpression of α-synuclein in primary and stem cell-derived oligodendrocytes severely impaired myelin formation, defining a novel α-synuclein-linked pathomechanism in MSA. We used the pro-myelinating activity of the muscarinic acetylcholine receptor antagonist benztropine to analyze the reversibility of the myelination deficit. Transcriptome profiling of primary pre-myelinating oligodendrocytes demonstrated that benztropine readjusts myelination-related processes such as cholesterol and membrane biogenesis, being compromised by oligodendrocytic α-synuclein. Additionally, benztropine restored the α-synuclein-induced myelination deficit of stem cell-derived oligodendrocytes. Strikingly, benztropine also ameliorated the myelin deficit in transgenic MSA mice, resulting in a prevention of neuronal cell loss. In conclusion, this study defines the

  4. The history of myelin.

    PubMed

    Boullerne, Anne Isabelle

    2016-09-01

    Andreas Vesalius is attributed the discovery of white matter in the 16th century but van Leeuwenhoek is arguably the first to have observed myelinated fibers in 1717. A globular myelin theory followed, claiming all elements of the nervous system except for Fontana's primitive cylinder with outer sheath in 1781. Remak's axon revolution in 1836 relegated myelin to the unknown. Ehrenberg described nerve tubes with double borders in 1833, and Schwann with nuclei in 1839, but the medullary sheath acquired its name of myelin, coined by Virchow, only in 1854. Thanks to Schultze's osmium specific staining in 1865, myelin designates the structure known today. The origin of myelin though was baffling. Only after Ranvier discovered a periodic segmentation, which came to us as nodes of Ranvier, did he venture suggesting in 1872 that the nerve internode was a fatty cell secreting myelin in cytoplasm. Ranvier's hypothesis was met with high skepticism, because nobody could see the cytoplasm, and the term Schwann cell very slowly emerged into the vocabulary with von Lenhossék in 1895. When Cajal finally admitted the concept of Schwann cell internode in 1912, he still firmly believed myelin was secreted by the axon. Del Río-Hortega re-discovered oligodendrocytes in 1919 (after Robertson in 1899) and named them oligodendroglia in 1921, thereby antagonizing Cajal for discovering a second cell type in his invisible third element. Penfield had to come to del Río-Hortega's rescue in 1924 for oligodendrocytes to be accepted. They jointly hypothesized myelin could be made by oligodendrocytes, considered the central equivalent of Schwann cells. Meanwhile myelin birefringence properties observed by Klebs in 1865 then Schmidt in 1924 confirmed its high fatty content, ascertained by biochemistry by Thudichum in 1884. The 20th century saw X-ray diffraction developed by Schmitt, who discovered in 1935 the crystal-like organization of this most peculiar structure, and devised the g

  5. Proline Substitutions and Threonine Pseudophosphorylation of the SH3 Ligand of 18.5-kDa Myelin Basic Protein Decrease Its Affinity for the Fyn-SH3 Domain and Alter Process Development and Protein Localization in Oligodendrocytes

    PubMed Central

    Smith, Graham S.T.; De Avila, Miguel; Paez, Pablo M.; Spreuer, Vilma; Wills, Melanie K.B.; Jones, Nina; Boggs, Joan M.; Harauz, George

    2012-01-01

    The developmentally regulated myelin basic proteins (MBPs), which arise from the golli (gene of oligodendrocyte lineage) complex, are highly positively charged, intrinsically disordered, multifunctional proteins having several alternatively spliced isoforms and posttranslational modifications, and they play key roles in myelin compaction. The classic 18.5-kDa MBP isoform has a proline-rich region comprising amino acids 92–99 (murine sequence –T92PRTPPPS99–) that contains a minimal SH3 ligand domain. We have previously shown that 18.5-kDa MBP binds to several SH3 domains, including that of Fyn, a member of the Src family of tyrosine kinases involved in a number of signaling pathways during CNS development. To determine the physiological role of this binding as well as the role of phosphorylation of Thr92 and Thr95, in the current study we have produced several MBP variants specifically targeting phosphorylation sites and key structural regions of MBP’s SH3 ligand domain. Using isothermal titration calorimetry, we have demonstrated that, compared with the wild-type protein, these variants have lower affinity for the SH3 domain of Fyn. Moreover, overexpression of N-terminal-tagged GFP versions in immortalized oligodendroglial N19 and N20.1 cell cultures results in aberrant elongation of membrane processes and increased branching complexity and inhibits the ability of MBP to decrease Ca2+ influx. Phosphorylation of Thr92 can also cause MBP to traffic to the nucleus, where it may participate in additional protein–protein interactions. Coexpression of MBP with a constitutively active form of Fyn kinase resulted in membrane process elaboration, a phenomenon that was abolished by point amino acid substitutions in MBP’s SH3 ligand domain. These results suggest that MBP’s SH3 ligand domain plays a key role in intracellular protein interactions in vivo and may be required for proper membrane elaboration of developing oligodendrocytes and, further, that

  6. Nfasc155H and MAG are specifically susceptible to detergent extraction in the absence of the myelin sphingolipid sulfatide

    PubMed Central

    Pomicter, AD; DeLoyht, JM; Hackett, AR; Purdie, N; Sato-Bigbee, C; Henderson, SC; Dupree, JL

    2015-01-01

    Mice incapable of synthesizing the myelin lipid sulfatide form paranodes that deteriorate with age. Similar instability also occurs in mice that lack contactin, contactin-associated protein or neurofascin155 (Nfasc155), the proteins that cluster in the paranode and form the junctional complex that mediates myelin-axon adhesion. In contrast to these proteins, sulfatide has not been shown to be enriched in the paranode nor has a sulfatide paranodal binding partner been identified; thus, it remains unclear how the absence of sulfatide results in compromised paranode integrity., Using an in situ extraction procedure, it has been reported that the absence of the myelin sphingolipids, galactocerebroside and sulfatide, increased the susceptibility of Nfasc155 to detergent extraction. Here, employing a similar approach, we demonstrate that in the presence of galactocerebroside but in the absence of sulfatide Nfasc155 is susceptible to detergent extraction. Furthermore, we use this in situ approach to show that stable association of myelin-associate glycoprotein (MAG) with the myelin membrane is sulfatide dependent while the membrane associations of myelin/oligodendrocyte glycoprotein, myelin basic protein and cyclic nucleotide phosphodiesterase are sulfatide independent. These findings indicate that myelin proteins maintain their membrane associations by different mechanisms. Moreover, the myelin proteins that cluster in the paranode and require sulfatide mediate myelin-axon adhesion. Additionally, the apparent dependency on sulfatide for maintaining Nfasc155 and MAG associations is intriguing since the fatty acid composition of sulfatide is altered and paranodal ultrastructure is compromised in multiple sclerosis. Thus, our findings present a potential link between sulfatide perturbation and myelin deterioration in multiple sclerosis. PMID:24081651

  7. Oligodendrocytes in HIV-associated pain pathogenesis

    PubMed Central

    Shi, Yuqiang; Shu, Jianhong; Liang, Zongsuo; Yuan, Subo

    2016-01-01

    Background Although the contributions of microglia and astrocytes to chronic pain pathogenesis have been a focal point of investigation in recent years, the potential role of oligodendrocytes, another major type of glial cells in the CNS that generates myelin, remains largely unknown. Results We report here that cell markers of the oligodendrocyte lineage, including NG2, PDGFRα, and Olig2, are significantly increased in the spinal dorsal horn of HIV patients who developed chronic pain. The levels of myelin proteins myelin basic protein and proteolipid protein are also aberrant in the spinal dorsal horn of “pain-positive” HIV patients. Similarly, the oligodendrocyte and myelin markers are up-regulated in the spinal dorsal horn of a mouse model of HIV-1 gp120-induced pain. Surprisingly, the expression of gp120-induced mechanical allodynia appears intact up to 4 h after myelin basic protein is knocked down or knocked out. Conclusion These findings suggest that oligodendrocytes are reactive during the pathogenesis of HIV-associated pain. However, interfering with myelination does not alter the induction of gp120-induced pain. PMID:27306410

  8. Adaptive myelination from fish to man.

    PubMed

    Baraban, Marion; Mensch, Sigrid; Lyons, David A

    2016-06-15

    Myelinated axons with nodes of Ranvier are an evolutionary elaboration common to essentially all jawed vertebrates. Myelin made by Schwann cells in our peripheral nervous system and oligodendrocytes in our central nervous system has been long known to facilitate rapid energy efficient nerve impulse propagation. However, it is now also clear, particularly in the central nervous system, that myelin is not a simple static insulator but that it is dynamically regulated throughout development and life. New myelin sheaths can be made by newly differentiating oligodendrocytes, and mature myelin sheaths can be stimulated to grow again in the adult. Furthermore, numerous studies in models from fish to man indicate that neuronal activity can affect distinct stages of oligodendrocyte development and the process of myelination itself. This begs questions as to how these effects of activity are mediated at a cellular and molecular level and whether activity-driven adaptive myelination is a feature common to all myelinated axons, or indeed all oligodendrocytes, or is specific to cells or circuits with particular functions. Here we review the recent literature on this topic, elaborate on the key outstanding questions in the field, and look forward to future studies that incorporate investigations in systems from fish to man that will provide further insight into this fundamental aspect of nervous system plasticity. This article is part of a Special Issue entitled SI: Myelin Evolution. PMID:26498877

  9. Molecular Basis of the interactions of the Nogo-66 Receptor and its homologue NgR2 with Myelin-Associated Glycoprotein: Development of NgROMNI-Fc a Novel Antagonist of CNS Myelin Inhibition

    PubMed Central

    Robak, Laurie A.; Venkatesh, Karthik; Lee, Hakjoo; Raiker, Stephen J.; Duan, Yuntao; Lee-Osbourne, Jane; Hofer, Thomas; Mage, Rose G.; Rader, Christoph; Giger, Roman J.

    2009-01-01

    Myelin-associated glycoprotein (MAG) is a sialic acid binding Ig-family lectin that functions in neuronal growth inhibition and stabilization of axon-glia interactions. The ectodomain of MAG is comprised of five Ig-like domains and employs neuronal cell-type specific mechanisms to signal growth inhibition. We show that the first three Ig-like domains of MAG bind with high-affinity and in a sialic acid dependent manner to the Nogo-66 receptor-1 (NgR1) and its homologue NgR2. Domains Ig3-Ig5 of MAG are sufficient to inhibit neurite outgrowth but fail to associate with NgR1 or NgR2. Nogo receptors are sialoglycoproteins comprised of 8.5 canonical leucine-rich repeats (LRR) flanked by LRR N-terminal (NT) and C-terminal (CT)-cap domains. The LRR cluster is connected through a stalk region to a membrane lipid anchor. The CT-cap domain and stalk region of NgR2, but not NgR1, are sufficient for MAG binding, and when expressed in neurons, exhibit constitutive growth inhibitory activity. The LRR cluster of NgR1 supports binding of Nogo-66, OMgp and MAG. Deletion of disulfide loop Cys309-Cys336 of NgR1 selectively increases its affinity for Nogo-66 and OMgp. A chimeric Nogo receptor variant (NgROMNI) in which Cys309-Cys336 is deleted and followed by a 13 amino acid MAG binding motif of the NgR2 stalk, shows superior binding of OMgp, Nogo-66, and MAG compared to wild-type NgR1 or NgR2. Soluble NgROMNI (NgROMNI-Fc) binds strongly to membrane bound inhibitors and promotes neurite outgrowth on both MAG and CNS myelin substrates. Thus, NgROMNI-Fc may offer therapeutic opportunities following nervous system injury or disease where myelin inhibits neuronal regeneration. PMID:19420245

  10. Cholesterol: a novel regulatory role in myelin formation.

    PubMed

    Saher, Gesine; Quintes, Susanne; Nave, Klaus-Armin

    2011-02-01

    Myelin consists of tightly compacted membranes that form an insulating sheath around axons. The function of myelin for rapid saltatory nerve conduction is dependent on its unique composition, highly enriched in glycosphingolipids and cholesterol. Cholesterol emerged as the only integral myelin component that is essential and rate limiting for the development of CNS and PNS myelin. Experiments with conditional mouse mutants that lack cholesterol biosynthesis in oligodendrocytes revealed that only minimal changes of the CNS myelin lipid composition are tolerated. In Schwann cells of the PNS, protein trafficking and myelin compaction depend on cholesterol. In this review, the authors summarize the role of cholesterol in myelin biogenesis and myelin disease. PMID:21343408

  11. CNS myelin induces regulatory functions of DC-SIGN-expressing, antigen-presenting cells via cognate interaction with MOG.

    PubMed

    García-Vallejo, J J; Ilarregui, J M; Kalay, H; Chamorro, S; Koning, N; Unger, W W; Ambrosini, M; Montserrat, V; Fernandes, R J; Bruijns, S C M; van Weering, J R T; Paauw, N J; O'Toole, T; van Horssen, J; van der Valk, P; Nazmi, K; Bolscher, J G M; Bajramovic, J; Dijkstra, C D; 't Hart, B A; van Kooyk, Y

    2014-06-30

    Myelin oligodendrocyte glycoprotein (MOG), a constituent of central nervous system myelin, is an important autoantigen in the neuroinflammatory disease multiple sclerosis (MS). However, its function remains unknown. Here, we show that, in healthy human myelin, MOG is decorated with fucosylated N-glycans that support recognition by the C-type lectin receptor (CLR) DC-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) on microglia and DCs. The interaction of MOG with DC-SIGN in the context of simultaneous TLR4 activation resulted in enhanced IL-10 secretion and decreased T cell proliferation in a DC-SIGN-, glycosylation-, and Raf1-dependent manner. Exposure of oligodendrocytes to proinflammatory factors resulted in the down-regulation of fucosyltransferase expression, reflected by altered glycosylation at the MS lesion site. Indeed, removal of fucose on myelin reduced DC-SIGN-dependent homeostatic control, and resulted in inflammasome activation, increased T cell proliferation, and differentiation toward a Th17-prone phenotype. These data demonstrate a new role for myelin glycosylation in the control of immune homeostasis in the healthy human brain through the MOG-DC-SIGN homeostatic regulatory axis, which is comprised by inflammatory insults that affect glycosylation. This phenomenon should be considered as a basis to restore immune tolerance in MS. PMID:24935259

  12. Signaling through ERK1/2 controls myelin thickness during myelin repair in the adult central nervous system.

    PubMed

    Fyffe-Maricich, Sharyl L; Schott, Alexandra; Karl, Molly; Krasno, Janet; Miller, Robert H

    2013-11-20

    Oligodendrocytes, the myelin-forming cells of the CNS, exquisitely tailor the thickness of individual myelin sheaths to the diameter of their target axons to maximize the speed of action potential propagation, thus ensuring proper neuronal connectivity and function. Following demyelinating injuries to the adult CNS, newly formed oligodendrocytes frequently generate new myelin sheaths. Following episodes of demyelination such as those that occur in patients with multiple sclerosis, however, the matching of myelin thickness to axon diameter fails leaving remyelinated axons with thin myelin sheaths potentially compromising function and leaving axons vulnerable to damage. How oligodendrocytes determine the appropriate thickness of myelin for an axon of defined size during repair is unknown and identifying the signals that regulate myelin thickness has obvious therapeutic implications. Here, we show that sustained activation of extracellular-regulated kinases 1 and 2 (ERK1/2) in oligodendrocyte lineage cells results in accelerated myelin repair after injury, and is sufficient for the generation of thick myelin sheaths around remyelinated axons in the adult mouse spinal cord. Our findings suggest a model where ERK1/2 MAP kinase signaling acts as a myelin thickness rheostat that instructs oligodendrocytes to generate axon-appropriate quantities of myelin. PMID:24259565

  13. Myelin glycolipids and their functions.

    PubMed

    Stoffel, W; Bosio, A

    1997-10-01

    During myelination, oligodendrocytes in the CNS and Schwann cells in the PNS synthesise myelin-specific proteins and lipids for the assembly of the axon myelin sheath. A dominant class of lipids in the myelin bilayer are the glycolipids, which include galactocerebroside (GalC), galactosulfatide (sGalC) and galactodiglyceride (GalDG). A promising approach for unravelling the roles played by various lipids in the myelin membrane involves knocking out the genes encoding important enzymes in lipid biosynthesis. The recent ablation of the ceramide galactosyltransferase ( cgt) gene in mice is the first example. The cgt gene encodes a key enzyme in glycolipid biosynthesis. Its absence causes glycolipid deficiency in the lipid bilayer, breakdown of axon insulation and loss of saltatory conduction. Additional knock-out studies should provide important insights into the various functions of glycolipids in myelinogenesis and myelin structure. PMID:9384539

  14. Adult sulfatide null mice maintain an increased number of oligodendrocytes

    PubMed Central

    Shroff, S; Pomicter, AD; Fox, MA; Henderson, SC; Dupree, JL

    2015-01-01

    The galactolipids galactocerebroside and sulfatide have been implicated in oligodendrocyte development and myelin formation. Much of the evidence for these galactolipid functions has been derived from antibody and chemical perturbation of cultured oligodendrocytes. Recently, we have observed abundant, unstable myelin and an increased number of oligodendrocytes in mice incapable of synthesizing the myelin galactolipids galactocerebroside and sulfatide. We have also reported that mice lacking sulfatide but that synthesize normal levels of galactocerebroside generate myelin with unstable paranodes while Hirahara et al. (2004) have shown an enhanced population of oligodendrocytes in the forebrain, medulla and cerebellum in immature sulfatide null mice. Here, we demonstrate that an increase in the number of oligodendrocytes in sulfatide null mice is not transient but is maintained through, at least, 7 months of age. Moreover, we demonstrate that the enhanced oligodendrocyte population results from, at least in part, increased cell survival. Finally, sulfatide null oligodendrocytes exhibit decreased morphological complexity, a feature which may relate to increased oligodendrocyte survival. PMID:19224580

  15. Myelination: actin disassembly leads the way

    PubMed Central

    Samanta, Jayshree; Salzer, James L.

    2016-01-01

    The mechanisms that drive the spiral wrapping of the myelin sheath around axons are poorly understood. Two papers in this issue of Developmental Cell demonstrate that actin disassembly, rather than actin assembly, predominates during oligodendrocyte maturation and is critical for the genesis of the central myelin sheath. PMID:26218317

  16. Early axonal damage and progressive myelin pathology define the kinetics of CNS histopathology in a mouse model of multiple sclerosis.

    PubMed

    Recks, Mascha S; Stormanns, Eva R; Bader, Jonas; Arnhold, Stefan; Addicks, Klaus; Kuerten, Stefanie

    2013-10-01

    Studies of MS histopathology are largely dependent on suitable animal models. While light microscopic analysis gives an overview of tissue pathology, it falls short in evaluating detailed changes in nerve fiber morphology. The ultrastructural data presented here and obtained from studies of myelin oligodendrocyte glycoprotein (MOG):35-55-induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice delineate that axonal damage and myelin pathology follow different kinetics in the disease course. While myelin pathology accumulated with disease progression, axonal damage coincided with the initial clinical disease symptoms and remained stable over time. This pattern applied both to irreversible axolysis and early axonal pathology. Notably, these histopathological patterns were reflected by the normal-appearing white matter (NAWM), suggesting that the NAWM is also in an active neurodegenerative state. The data underline the need for neuroprotection in MS and suggest the MOG model as a highly valuable tool for the assessment of different therapeutic strategies. PMID:23899992

  17. Transferrin receptor and ferritin-H are developmentally regulated in oligodendrocyte lineage cells.

    PubMed

    Li, Yunxia; Guan, Qiang; Chen, Yuhui; Han, Hongjie; Liu, Wuchao; Nie, Zhiyu

    2013-01-01

    Iron is an essential trophic element that is required for cell viability and differentiation, especially in oligodendrocytes, which consume relatively high rates of energy to produce myelin. Multiple iron metabolism proteins are expressed in the brain including transferrin receptor and ferritin-H. However, it is still unknown whether they are developmentally regulated in oligodendrocyte lineage cells for myelination. Here, using an in vitro cultured differentiation model of oligodendrocytes, we found that both transferrin receptor and ferritin-H are significantly upregulated during oligodendrocyte maturation, implying the essential role of iron in the development of oligodendrocytes. Additional different doses of Fe(3+) in the cultured medium did not affect oligodendrocyte precursor cell maturation or ferritin-H expression but decreased the expression of the transferrin receptor. These results indicate that upregulation of both transferrin receptor and ferritin-H contributes to maturation and myelination of oligodendrocyte precursor cells. PMID:25206366

  18. Neuronal activity biases axon selection for myelination in vivo

    PubMed Central

    Hines, Jacob H.; Ravanelli, Andrew M.; Schwindt, Rani; Scott, Ethan K.; Appel, Bruce

    2015-01-01

    An essential feature of vertebrate neural development is ensheathment of axons with myelin, an insulating membrane formed by oligodendrocytes. Not all axons are myelinated, but mechanisms directing myelination of specific axons are unknown. Using zebrafish we show that activity-dependent secretion stabilizes myelin sheath formation on select axons. When VAMP2-dependent exocytosis is silenced in single axons, oligodendrocytes preferentially ensheath neighboring axons. Nascent sheaths formed on silenced axons are shorter in length, but when activity of neighboring axons is also suppressed, inhibition of sheath growth is relieved. Using in vivo time-lapse microscopy, we show that only 25% of oligodendrocyte processes that initiate axon wrapping are stabilized during normal development, and that initiation does not require activity. Instead, oligodendrocyte processes wrapping silenced axons are retracted more frequently. We propose that axon selection for myelination results from excessive and indiscriminate initiation of wrapping followed by refinement that is biased by activity-dependent secretion from axons. PMID:25849987

  19. Long-term efficacy of rituximab in IgM anti-myelin-associated glycoprotein neuropathy: RIMAG follow-up study.

    PubMed

    Iancu Ferfoglia, Ruxandra; Guimarães-Costa, Raquel; Viala, Karine; Musset, Lucile; Neil, Jean; Marin, Benoit; Léger, Jean-Marc

    2016-03-01

    The Rituximab vs. Placebo in Polyneuropathy Associated With Anti-MAG IgM Monoclonal Gammopathy (RIMAG) study showed no improvement using the inflammatory neuropathy cause and treatment sensory score (ISS) as primary outcome in patients with IgM anti-myelin-associated glycoprotein neuropathy (IgM anti-MAG neuropathy) treated with rituximab, when compared with placebo. However, some secondary outcomes seemed to improve in the per protocol analysis. Patients from one participating center in the RIMAG study underwent a new evaluation after a median follow-up of 6 (interquartile range (IQR) 4.9; 6.5) years, using the same outcome measures used in the original study. Data were recorded in seven rituximab patients (group 1) and in eight placebo patients (group 2). In group 2, six of eight patients received immunotherapy during follow-up, while only two of seven did in group 1. No significant change was observed in either the ISS or the secondary outcomes in both groups, with the exception of worsening in the 10-m walk time in group 2 (p = 0.016). The RIMAG follow-up study failed to find any significant change in most outcome measures in patients from the RIMAG study, some of them having received new immunotherapies. This study stresses the lack of useful clinical scales sensitive enough to capture small, even meaningful, improvement in IgM anti-MAG neuropathy. PMID:26748872

  20. A role for Sec8 in oligodendrocyte morphological differentiation.

    PubMed

    Anitei, Mihaela; Ifrim, Marius; Ewart, Marie-Ann; Cowan, Ann E; Carson, John H; Bansal, Rashmi; Pfeiffer, Steven E

    2006-03-01

    In the central nervous system, oligodendrocytes synthesize vast amounts of myelin, a multilamellar membrane wrapped around axons that dramatically enhances nerve transmission. A complex apparatus appears to coordinate trafficking of proteins and lipids during myelin synthesis, but the molecular interactions involved are not well understood. We demonstrate that oligodendrocytes express several key molecules necessary for the targeting of transport vesicles to areas of rapid membrane growth, including the exocyst components Sec8 and Sec6 and the multidomain scaffolding proteins CASK and Mint1. Sec8 overexpression significantly promotes oligodendrocyte morphological differentiation and myelin-like membrane formation in vitro; conversely, siRNA-mediated interference with Sec8 expression inhibits this process, and anti-Sec8 antibody induces a reduction in oligodendrocyte areas. In addition, Sec8 colocalizes, coimmunoprecipitates and cofractionates with the major myelin protein OSP/Claudin11 and with CASK in oligodendrocytes. These results suggest that Sec8 plays a central role in oligodendrocyte membrane formation by regulating the recruitment of vesicles that transport myelin proteins such as OSP/Claudin11 to sites of membrane growth. PMID:16478790

  1. The myelinated axon is dependent on the myelinating cell for support and maintenance: molecules involved.

    PubMed

    Edgar, J M; Garbern, J

    2004-06-01

    The myelin-forming cells, oligodendrocytes and Schwann cells, extend processes that spirally wrap axons and provide the insulation that allows rapid saltatory conduction. Recent data suggest a further role for the myelin-forming cells in axonal support and maintenance. This Mini-Review summarises some of the data that support this view and highlights the molecules involved. PMID:15139018

  2. PI(3,5)P2 biosynthesis regulates oligodendrocyte differentiation by intrinsic and extrinsic mechanisms

    PubMed Central

    Mironova, Yevgeniya A; Lenk, Guy M; Lin, Jing-Ping; Lee, Seung Joon; Twiss, Jeffery L; Vaccari, Ilaria; Bolino, Alessandra; Havton, Leif A; Min, Sang H; Abrams, Charles S; Shrager, Peter; Meisler, Miriam H; Giger, Roman J

    2016-01-01

    Proper development of the CNS axon-glia unit requires bi-directional communication between axons and oligodendrocytes (OLs). We show that the signaling lipid phosphatidylinositol-3,5-bisphosphate [PI(3,5)P2] is required in neurons and in OLs for normal CNS myelination. In mice, mutations of Fig4, Pikfyve or Vac14, encoding key components of the PI(3,5)P2 biosynthetic complex, each lead to impaired OL maturation, severe CNS hypomyelination and delayed propagation of compound action potentials. Primary OLs deficient in Fig4 accumulate large LAMP1+ and Rab7+ vesicular structures and exhibit reduced membrane sheet expansion. PI(3,5)P2 deficiency leads to accumulation of myelin-associated glycoprotein (MAG) in LAMP1+perinuclear vesicles that fail to migrate to the nascent myelin sheet. Live-cell imaging of OLs after genetic or pharmacological inhibition of PI(3,5)P2 synthesis revealed impaired trafficking of plasma membrane-derived MAG through the endolysosomal system in primary cells and brain tissue. Collectively, our studies identify PI(3,5)P2 as a key regulator of myelin membrane trafficking and myelinogenesis. DOI: http://dx.doi.org/10.7554/eLife.13023.001 PMID:27008179

  3. PI(3,5)P2 biosynthesis regulates oligodendrocyte differentiation by intrinsic and extrinsic mechanisms.

    PubMed

    Mironova, Yevgeniya A; Lenk, Guy M; Lin, Jing-Ping; Lee, Seung Joon; Twiss, Jeffery L; Vaccari, Ilaria; Bolino, Alessandra; Havton, Leif A; Min, Sang H; Abrams, Charles S; Shrager, Peter; Meisler, Miriam H; Giger, Roman J

    2016-01-01

    Proper development of the CNS axon-glia unit requires bi-directional communication between axons and oligodendrocytes (OLs). We show that the signaling lipid phosphatidylinositol-3,5-bisphosphate [PI(3,5)P2] is required in neurons and in OLs for normal CNS myelination. In mice, mutations of Fig4, Pikfyve or Vac14, encoding key components of the PI(3,5)P2 biosynthetic complex, each lead to impaired OL maturation, severe CNS hypomyelination and delayed propagation of compound action potentials. Primary OLs deficient in Fig4 accumulate large LAMP1(+) and Rab7(+) vesicular structures and exhibit reduced membrane sheet expansion. PI(3,5)P2 deficiency leads to accumulation of myelin-associated glycoprotein (MAG) in LAMP1(+)perinuclear vesicles that fail to migrate to the nascent myelin sheet. Live-cell imaging of OLs after genetic or pharmacological inhibition of PI(3,5)P2 synthesis revealed impaired trafficking of plasma membrane-derived MAG through the endolysosomal system in primary cells and brain tissue. Collectively, our studies identify PI(3,5)P2 as a key regulator of myelin membrane trafficking and myelinogenesis. PMID:27008179

  4. Purification of oligodendrocyte lineage cells from mouse cortices by immunopanning.

    PubMed

    Emery, Ben; Dugas, Jason C

    2013-09-01

    Oligodendrocytes are the myelinating cells of the vertebrate central nervous system, responsible for generating the myelin sheath necessary for saltatory conduction. The use of increasingly sophisticated genetic tools, particularly in mice, has vastly increased our understanding of the molecular mechanisms that regulate development of the oligodendrocyte lineage. This increased reliance on the mouse as a genetic model has led to a need for the development of culture methods to allow the use of mouse cells in vitro as well as in vivo. Here, we present a protocol for the isolation of different stages of the oligodendrocyte lineage, oligodendrocyte precursor cells (OPCs) and/or postmitotic oligodendrocytes, from the postnatal mouse cortex using immunopanning. This protocol allows for the subsequent culture or biochemical analysis of these cells. PMID:24003195

  5. CNS myelin wrapping is driven by actin disassembly.

    PubMed

    Zuchero, J Bradley; Fu, Meng-Meng; Sloan, Steven A; Ibrahim, Adiljan; Olson, Andrew; Zaremba, Anita; Dugas, Jason C; Wienbar, Sophia; Caprariello, Andrew V; Kantor, Christopher; Leonoudakis, Dmitri; Leonoudakus, Dmitri; Lariosa-Willingham, Karen; Kronenberg, Golo; Gertz, Karen; Soderling, Scott H; Miller, Robert H; Barres, Ben A

    2015-07-27

    Myelin is essential in vertebrates for the rapid propagation of action potentials, but the molecular mechanisms driving its formation remain largely unknown. Here we show that the initial stage of process extension and axon ensheathment by oligodendrocytes requires dynamic actin filament assembly by the Arp2/3 complex. Unexpectedly, subsequent myelin wrapping coincides with the upregulation of actin disassembly proteins and rapid disassembly of the oligodendrocyte actin cytoskeleton and does not require Arp2/3. Inducing loss of actin filaments drives oligodendrocyte membrane spreading and myelin wrapping in vivo, and the actin disassembly factor gelsolin is required for normal wrapping. We show that myelin basic protein, a protein essential for CNS myelin wrapping whose role has been unclear, is required for actin disassembly, and its loss phenocopies loss of actin disassembly proteins. Together, these findings provide insight into the molecular mechanism of myelin wrapping and identify it as an actin-independent form of mammalian cell motility. PMID:26166300

  6. Myelin, myelin-related disorders, and psychosis.

    PubMed

    Mighdoll, Michelle I; Tao, Ran; Kleinman, Joel E; Hyde, Thomas M

    2015-01-01

    The neuropathological basis of schizophrenia and related psychoses remains elusive despite intensive scientific investigation. Symptoms of psychosis have been reported in a number of conditions where normal myelin development is interrupted. The nature, location, and timing of white matter pathology seem to be key factors in the development of psychosis, especially during the critical adolescent period of association area myelination. Numerous lines of evidence implicate myelin and oligodendrocyte function as critical processes that could affect neuronal connectivity, which has been implicated as a central abnormality in schizophrenia. Phenocopies of schizophrenia with a known pathological basis involving demyelination or dysmyelination may offer insights into the biology of schizophrenia itself. This article reviews the pathological changes in white matter of patients with schizophrenia, as well as demyelinating diseases associated with psychosis. In an attempt to understand the potential role of dysmyelination in schizophrenia, we outline the evidence from a number of both clinically-based and post-mortem studies that provide evidence that OMR genes are genetically associated with increased risk for schizophrenia. To further understand the implication of white matter dysfunction and dysmyelination in schizophrenia, we examine diffusion tensor imaging (DTI), which has shown volumetric and microstructural white matter differences in patients with schizophrenia. While classical clinical-neuropathological correlations have established that disruption in myelination can produce a high fidelity phenocopy of psychosis similar to schizophrenia, the role of dysmyelination in schizophrenia remains controversial. PMID:25449713

  7. The transcriptome of mouse central nervous system myelin

    PubMed Central

    Thakurela, Sudhir; Garding, Angela; Jung, Ramona B.; Müller, Christina; Goebbels, Sandra; White, Robin; Werner, Hauke B.; Tiwari, Vijay K.

    2016-01-01

    Rapid nerve conduction in the CNS is facilitated by insulation of axons with myelin, a specialized oligodendroglial compartment distant from the cell body. Myelin is turned over and adapted throughout life; however, the molecular and cellular basis of myelin dynamics remains elusive. Here we performed a comprehensive transcriptome analysis (RNA-seq) of myelin biochemically purified from mouse brains at various ages and find a surprisingly large pool of transcripts enriched in myelin. Further computational analysis showed that the myelin transcriptome is closely related to the myelin proteome but clearly distinct from the transcriptomes of oligodendrocytes and brain tissues, suggesting a highly selective incorporation of mRNAs into the myelin compartment. The mRNA-pool in myelin displays maturation-dependent dynamic changes of composition, abundance, and functional associations; however ageing-dependent changes after 6 months were minor. We suggest that this transcript pool enables myelin turnover and the local adaptation of individual pre-existing myelin sheaths. PMID:27173133

  8. The transcriptome of mouse central nervous system myelin.

    PubMed

    Thakurela, Sudhir; Garding, Angela; Jung, Ramona B; Müller, Christina; Goebbels, Sandra; White, Robin; Werner, Hauke B; Tiwari, Vijay K

    2016-01-01

    Rapid nerve conduction in the CNS is facilitated by insulation of axons with myelin, a specialized oligodendroglial compartment distant from the cell body. Myelin is turned over and adapted throughout life; however, the molecular and cellular basis of myelin dynamics remains elusive. Here we performed a comprehensive transcriptome analysis (RNA-seq) of myelin biochemically purified from mouse brains at various ages and find a surprisingly large pool of transcripts enriched in myelin. Further computational analysis showed that the myelin transcriptome is closely related to the myelin proteome but clearly distinct from the transcriptomes of oligodendrocytes and brain tissues, suggesting a highly selective incorporation of mRNAs into the myelin compartment. The mRNA-pool in myelin displays maturation-dependent dynamic changes of composition, abundance, and functional associations; however ageing-dependent changes after 6 months were minor. We suggest that this transcript pool enables myelin turnover and the local adaptation of individual pre-existing myelin sheaths. PMID:27173133

  9. Comparative Effects of Human Neural Stem Cells and Oligodendrocyte Progenitor Cells on the Neurobehavioral Disorders of Experimental Autoimmune Encephalomyelitis Mice

    PubMed Central

    Bae, Dae-Kwon; Park, Dongsun; Lee, Sun Hee; Yang, Goeun; Kyung, Jangbeen; Kim, Dajeong; Shin, Kyungha; Choi, Ehn-Kyoung; Kim, Gonhyung; Hong, Jin Tae; Kim, Seung U.

    2016-01-01

    Since multiple sclerosis (MS) is featured with widespread demyelination caused by autoimmune response, we investigated the recovery effects of F3.olig2 progenitors, established by transducing human neural stem cells (F3 NSCs) with Olig2 transcription factor, in myelin oligodendrocyte glycoprotein- (MOG-) induced experimental autoimmune encephalomyelitis (EAE) model mice. Six days after EAE induction, F3 or F3.olig2 cells (1 × 106/mouse) were intravenously transplanted. MOG-injected mice displayed severe neurobehavioral deficits which were remarkably attenuated and restored by cell transplantation, in which F3.olig2 cells were superior to its parental F3 cells. Transplanted cells migrated to the injured spinal cord, matured to oligodendrocytes, and produced myelin basic proteins (MBP). The F3.olig2 cells expressed growth and neurotrophic factors including brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), ciliary neurotrophic factor (CNTF), and leukemia inhibitory factor (LIF). In addition, the transplanted cells markedly attenuated inflammatory cell infiltration, reduced cytokine levels in the spinal cord and lymph nodes, and protected host myelins. The results indicate that F3.olig2 cells restore neurobehavioral symptoms of EAE mice by regulating autoimmune inflammatory responses as well as by stimulating remyelination and that F3.olig2 progenitors could be a candidate for the cell therapy of demyelinating diseases including MS. PMID:27429621

  10. Diversity Matters: A Revised Guide to Myelination.

    PubMed

    Tomassy, Giulio Srubek; Dershowitz, Lori Bowe; Arlotta, Paola

    2016-02-01

    The evolutionary success of the vertebrate nervous system is largely due to a unique structural feature--the myelin sheath, a fatty envelope that surrounds the axons of neurons. By increasing the speed by which electrical signals travel along axons, myelin facilitates neuronal communication between distant regions of the nervous system. We review the cellular and molecular mechanisms that regulate the development of myelin as well as its homeostasis in adulthood. We discuss how finely tuned neuron-oligodendrocyte interactions are central to myelin formation during development and in the adult, and how these interactions can have profound implications for the plasticity of the adult brain. We also speculate how the functional diversity of both neurons and oligodendrocytes may impact on the myelination process in both health and disease. PMID:26442841

  11. Antigen-oriented T cell migration contributes to myelin peptide induced-EAE and immune tolerance.

    PubMed

    Zheng, Peiguo; Fu, Hanxiao; Wei, Gaohui; Wei, Zhongwei; Zhang, Junhua; Ma, Xuehan; Rui, Dong; Meng, Xianchun; Ming, Liang

    2016-08-01

    Treatment with soluble myelin peptide can efficiently and specifically induce tolerance to demyelination autoimmune diseases including multiple sclerosis, however the mechanism underlying this therapeutic effect remains to be elucidated. In actively induced mouse model of experimental autoimmune encephalomyelitis (EAE) we analyzed T cell and innate immune cell responses in the central nervous system (CNS) and spleen after intraperitoneal (i.p.) infusion of myelin oligodendrocyte glycoprotein (MOG). We found that i.p. MOG infusion blocked effector T cell recruitment to the CNS and protected mice from EAE and lymphoid organ atrophy. Innate immune CD11b(+) cells preferentially recruited MOG-specific effector T cells, particularly when activated to become competent antigen presenting cells (APCs). During EAE development, mature APCs were enriched in the CNS rather than in the spleen, attracting effector T cells to the CNS. Increased myelin antigen exposure induced CNS-APC maturation, recruiting additional effector T cells to the CNS, causing symptoms of disease. MOG triggered functional maturation of splenic APCs. MOG presenting APCs interacted with MOG-specific T cells in the spleen, aggregating to cluster around CD11b(+) cells, and were trapped in the periphery. This process was MHC II dependent as an MHC II directed antibody blocked CD4(+) T cell cluster formation. These findings highlight the role of myelin peptide-loaded APCs in myelin peptide-induced EAE and immune tolerance. PMID:27327113

  12. mTOR: a link from the extracellular milieu to transcriptional regulation of oligodendrocyte development

    PubMed Central

    Wood, Teresa L.; Bercury, Kathryn K.; Cifelli, Stacey E.; Mursch, Lauren E.; Min, Jungsoo; Dai, Jinxiang; Macklin, Wendy B.

    2013-01-01

    Oligodendrocyte development is controlled by numerous extracellular signals that regulate a series of transcription factors that promote the differentiation of oligodendrocyte progenitor cells to myelinating cells in the central nervous system. A major element of this regulatory system that has only recently been studied is the intracellular signalling from surface receptors to transcription factors to down-regulate inhibitors and up-regulate inducers of oligodendrocyte differentiation and myelination. The current review focuses on one such pathway: the mTOR (mammalian target of rapamycin) pathway, which integrates signals in many cell systems and induces cell responses including cell proliferation and cell differentiation. This review describes the known functions of mTOR as they relate to oligodendrocyte development, and its recently discovered impact on oligodendrocyte differentiation and myelination. A potential model for its role in oligodendrocyte development is proposed. PMID:23421405

  13. Cord blood administration induces oligodendrocyte survival through alterations in gene expression

    PubMed Central

    Rowe, D.D.; Leonardo, C.C.; Hall, A.A.; Shahaduzzaman, M.D.; Collier, L.A.; Willing, A.E.; Pennypacker, K.R.

    2010-01-01

    Oligodendrocytes (OLs), the predominant cell type found in cerebral white matter, are essential for structural integrity and proper neural signaling. Very little is known concerning stroke-induced OL dysfunction. Our laboratory has shown that infusion of human umbilical cord blood (HUCB) cells protects striatal white matter tracts in vivo and directly protects mature primary OL cultures from oxygen glucose deprivation (OGD). Microarray studies of RNA prepared from OL cultures subjected to OGD and treated with HUCB cells showed an increase in the expression of 33 genes associated with OL proliferation, survival, and repair functions, such as myelination. The microarray results were verified using quantitative RT-PCR for the following eight genes: U2AF homology motif kinase 1 (Uhmk1), insulin induce gene 1 (Insig1), metallothionein ( Mt3), tetraspanin 2 (Tspan2), peroxiredoxin 4 (Prdx4), stathmin-like 2 (Stmn2), myelin oligodendrocyte glycoprotein (MOG), and versican (Vcan). Immunohistochemistry showed that MOG, Prdx4, Uhmk1, Insig1 and Mt3 protein expression were upregluated in the ipsilateral white matter tracts of rats infused with HUCB cells 48 hrs after middle cerebral artery occlusion (MCAO). Furthermore, promoter region analysis of these genes revealed common transcription factor binding sites, providing insight into the shared signal transduction pathways activated by HUCB cells to enhance transcription of these genes. These results show expression of genes induced by HUCB cell therapy that could confer oligoprotection from ischemia. PMID:20883670

  14. Myelinogenesis and axonal recognition by oligodendrocytes in brain are uncoupled in Olig1-null mice.

    PubMed

    Xin, Mei; Yue, Tao; Ma, Zhenyi; Wu, Fen-fen; Gow, Alexander; Lu, Q Richard

    2005-02-01

    Myelin-forming oligodendrocytes facilitate saltatory nerve conduction and support neuronal functions in the mammalian CNS. Although the processes of oligodendrogliogenesis and differentiation from neural progenitor cells have come to light in recent years, the molecular mechanisms underlying oligodendrocyte myelinogenesis are poorly defined. Herein, we demonstrate the pivotal role of the basic helix-loop-helix transcription factor, Olig1, in oligodendrocyte myelinogenesis in brain development. Mice lacking a functional Olig1 gene develop severe neurological deficits and die in the third postnatal week. In the brains of these mice, expression of myelin-specific genes is abolished, whereas the formation of oligodendrocyte progenitors is not affected. Furthermore, multilamellar wrapping of myelin membranes around axons does not occur, despite recognition and contact of axons by oligodendrocytes, and Olig1-null mice develop widespread progressive axonal degeneration and gliosis. In contrast, myelin sheaths are formed in the spinal cord, although the extent of myelination is severely reduced. At the molecular level, we find that Olig1 regulates transcription of the major myelin-specific genes, Mbp, Plp1, and Mag, and suppresses expression of a major astrocyte-specific gene, Gfap. Together, our data indicate that Olig1 is a central regulator of oligodendrocyte myelinogenesis in brain and that axonal recognition and myelination by oligodendrocytes are separable processes. PMID:15703389

  15. Clemastine Enhances Myelination in the Prefrontal Cortex and Rescues Behavioral Changes in Socially Isolated Mice

    PubMed Central

    Dupree, Jeffrey L.; Gacias, Mar; Frawley, Rebecca; Sikder, Tamjeed; Naik, Payal; Casaccia, Patrizia

    2016-01-01

    Altered myelin structure and oligodendrocyte function have been shown to correlate with cognitive and motor dysfunction and deficits in social behavior. We and others have previously demonstrated that social isolation in mice induced behavioral, transcriptional, and ultrastructural changes in oligodendrocytes of the prefrontal cortex (PFC). However, whether enhancing myelination and oligodendrocyte differentiation could be beneficial in reversing such changes remains unexplored. To test this hypothesis, we orally administered clemastine, an antimuscarinic compound that has been shown to enhance oligodendrocyte differentiation and myelination in vitro, for 2 weeks in adult mice following social isolation. Clemastine successfully reversed social avoidance behavior in mice undergoing prolonged social isolation. Impaired myelination was rescued by oral clemastine treatment, and was associated with enhanced oligodendrocyte progenitor differentiation and epigenetic changes. Clemastine induced higher levels of repressive histone methylation (H3K9me3), a marker for heterochromatin, in oligodendrocytes, but not neurons, of the PFC. This was consistent with the capability of clemastine in elevating H3K9 histone methyltransferases activity in cultured primary mouse oligodendrocytes, an effect that could be antagonized by cotreatment with muscarine. Our data suggest that promoting adult myelination is a potential strategy for reversing depressive-like social behavior. SIGNIFICANCE STATEMENT Oligodendrocyte development and myelination are highly dynamic processes influenced by experience and neuronal activity. However, whether enhancing myelination and oligodendrocyte differentiation is beneficial to treat depressive-like behavior has been unexplored. Mice undergoing prolonged social isolation display impaired myelination in the prefrontal cortex. Clemastine, a Food and Drug Administration-approved antimuscarinic compound that has been shown to enhance myelination under

  16. Clemastine Enhances Myelination in the Prefrontal Cortex and Rescues Behavioral Changes in Socially Isolated Mice.

    PubMed

    Liu, Jia; Dupree, Jeffrey L; Gacias, Mar; Frawley, Rebecca; Sikder, Tamjeed; Naik, Payal; Casaccia, Patrizia

    2016-01-20

    Altered myelin structure and oligodendrocyte function have been shown to correlate with cognitive and motor dysfunction and deficits in social behavior. We and others have previously demonstrated that social isolation in mice induced behavioral, transcriptional, and ultrastructural changes in oligodendrocytes of the prefrontal cortex (PFC). However, whether enhancing myelination and oligodendrocyte differentiation could be beneficial in reversing such changes remains unexplored. To test this hypothesis, we orally administered clemastine, an antimuscarinic compound that has been shown to enhance oligodendrocyte differentiation and myelination in vitro, for 2 weeks in adult mice following social isolation. Clemastine successfully reversed social avoidance behavior in mice undergoing prolonged social isolation. Impaired myelination was rescued by oral clemastine treatment, and was associated with enhanced oligodendrocyte progenitor differentiation and epigenetic changes. Clemastine induced higher levels of repressive histone methylation (H3K9me3), a marker for heterochromatin, in oligodendrocytes, but not neurons, of the PFC. This was consistent with the capability of clemastine in elevating H3K9 histone methyltransferases activity in cultured primary mouse oligodendrocytes, an effect that could be antagonized by cotreatment with muscarine. Our data suggest that promoting adult myelination is a potential strategy for reversing depressive-like social behavior. Significance statement: Oligodendrocyte development and myelination are highly dynamic processes influenced by experience and neuronal activity. However, whether enhancing myelination and oligodendrocyte differentiation is beneficial to treat depressive-like behavior has been unexplored. Mice undergoing prolonged social isolation display impaired myelination in the prefrontal cortex. Clemastine, a Food and Drug Administration-approved antimuscarinic compound that has been shown to enhance myelination under

  17. Oligodendroglia and Myelin in Neurodegenerative Diseases: More Than Just Bystanders?

    PubMed

    Ettle, Benjamin; Schlachetzki, Johannes C M; Winkler, Jürgen

    2016-07-01

    Oligodendrocytes, the myelinating cells of the central nervous system, mediate rapid action potential conduction and provide trophic support for axonal as well as neuronal maintenance. Their progenitor cell population is widely distributed in the adult brain and represents a permanent cellular reservoir for oligodendrocyte replacement and myelin plasticity. The recognition of oligodendrocytes, their progeny, and myelin as contributing factors for the pathogenesis and the progression of neurodegenerative disease has recently evolved shaping our understanding of these disorders. In the present review, we aim to highlight studies on oligodendrocytes and their progenitors in neurodegenerative diseases. We dissect oligodendroglial biology and illustrate evolutionary aspects in regard to their importance for neuronal functionality and maintenance of neuronal circuitries. After covering recent studies on oligodendroglia in different neurodegenerative diseases mainly in view of their function as myelinating cells, we focus on the alpha-synucleinopathy multiple system atrophy, a prototypical disorder with a well-defined oligodendroglial pathology. PMID:25966971

  18. Mechanostimulation Promotes Nuclear and Epigenetic Changes in Oligodendrocytes

    PubMed Central

    Hernandez, Marylens; Patzig, Julia; Mayoral, Sonia R.; Costa, Kevin D.; Chan, Jonah R.

    2016-01-01

    Oligodendrocyte progenitors respond to biophysical or mechanical signals, and it has been reported that mechanostimulation modulates cell proliferation, migration, and differentiation. Here we report the effect of three mechanical stimuli on mouse oligodendrocyte progenitor differentiation and identify the molecular components of the linker of nucleoskeleton and cytoskeleton (LINC) complex (i.e., SYNE1) as transducers of mechanical signals to the nucleus, where they modulate the deposition of repressive histone marks and heterochromatin formation. The expression levels of LINC components increased during progenitor differentiation and silencing the Syne1 gene resulted in aberrant histone marks deposition, chromatin reorganization and impaired myelination. We conclude that spatial constraints, via the actin cytoskeleton and LINC complex, mediate nuclear changes in oligodendrocyte progenitors that favor a default pathway of differentiation. SIGNIFICANCE STATEMENT It is recognized that oligodendrocyte progenitors are mechanosensitive cells. However, the molecular mechanisms translating mechanical stimuli into oligodendrocyte differentiation remain elusive. This study identifies components of the mechanotransduction pathway in the oligodendrocyte lineage. PMID:26791211

  19. The adhesion GPCR Gpr56 regulates oligodendrocyte development via interactions with Gα12/13 and RhoA

    PubMed Central

    Ackerman, Sarah D.; Garcia, Cynthia; Piao, Xianhua; Gutmann, David H.; Monk, Kelly R.

    2014-01-01

    In the vertebrate central nervous system, myelinating oligodendrocytes are postmitotic and derive from proliferative oligodendrocyte precursor cells (OPCs). The molecular mechanisms that govern oligodendrocyte development are incompletely understood, but recent studies implicate the adhesion class of G protein-coupled receptors (aGPCRs) as important regulators of myelination. Here, we use zebrafish and mouse models to dissect the function of the aGPCR Gpr56 in oligodendrocyte development. We show that gpr56 is expressed during early stages of oligodendrocyte development. Additionally, we observe a significant reduction of mature oligodendrocyte number and of myelinated axons in gpr56 zebrafish mutants. This reduction results from decreased OPC proliferation, rather than increased cell death or altered neural precursor differentiation potential. Finally, we show that these functions are mediated by Gα12/13 proteins and Rho activation. Together, our data establish Gpr56 as a regulator of oligodendrocyte development. PMID:25607772

  20. The transcription factors Sox10 and Myrf define an essential regulatory network module in differentiating oligodendrocytes.

    PubMed

    Hornig, Julia; Fröb, Franziska; Vogl, Michael R; Hermans-Borgmeyer, Irm; Tamm, Ernst R; Wegner, Michael

    2013-10-01

    Myelin is essential for rapid saltatory conduction and is produced by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. In both cell types the transcription factor Sox10 is an essential component of the myelin-specific regulatory network. Here we identify Myrf as an oligodendrocyte-specific target of Sox10 and map a Sox10 responsive enhancer to an evolutionarily conserved element in intron 1 of the Myrf gene. Once induced, Myrf cooperates with Sox10 to implement the myelination program as evident from the physical interaction between both proteins and the synergistic activation of several myelin-specific genes. This is strongly reminiscent of the situation in Schwann cells where Sox10 first induces and then cooperates with Krox20 during myelination. Our analyses indicate that the regulatory network for myelination in oligodendrocytes is organized along similar general principles as the one in Schwann cells, but is differentially implemented. PMID:24204311

  1. Induction of myelination in the central nervous system by electrical activity.

    PubMed Central

    Demerens, C; Stankoff, B; Logak, M; Anglade, P; Allinquant, B; Couraud, F; Zalc, B; Lubetzki, C

    1996-01-01

    The oligodendrocyte is the myelin-forming cell in the central nervous system. Despite the close interaction between axons and oligodendrocytes, there is little evidence that neurons influence myelinogenesis. On the contrary, newly differentiated oligodendrocytes, which mature in culture in the total absence of neurons, synthesize the myelin-specific constituents of oligodendrocytes differentiated in vivo and even form myelin-like figures. Neuronal electrical activity may be required, however, for the appropriate formation of the myelin sheath. To investigate the role of electrical activity on myelin formation, we have used highly specific neurotoxins, which can either block (tetrodotoxin) or increase (alpha-scorpion toxin) the firing of neurons. We show that myelination can be inhibited by blocking the action potential of neighboring axons or enhanced by increasing their electrical activity, clearly linking neuronal electrical activity to myelinogenesis. Images Fig. 1 Fig. 2 Fig. 3 PMID:8790426

  2. Dimethyl fumarate modulates antioxidant and lipid metabolism in oligodendrocytes.

    PubMed

    Huang, He; Taraboletti, Alexandra; Shriver, Leah P

    2015-08-01

    Oxidative stress contributes to pathology associated with inflammatory brain disorders and therapies that upregulate antioxidant pathways may be neuroprotective in diseases such as multiple sclerosis. Dimethyl fumarate, a small molecule therapeutic for multiple sclerosis, activates cellular antioxidant signaling pathways and may promote myelin preservation. However, it is still unclear what mechanisms may underlie this neuroprotection and whether dimethyl fumarate affects oligodendrocyte responses to oxidative stress. Here, we examine metabolic alterations in oligodendrocytes treated with dimethyl fumarate by using a global metabolomic platform that employs both hydrophilic interaction liquid chromatography-mass spectrometry and shotgun lipidomics. Prolonged treatment of oligodendrocytes with dimethyl fumarate induces changes in citric acid cycle intermediates, glutathione, and lipids, indicating that this compound can directly impact oligodendrocyte metabolism. These metabolic alterations are also associated with protection from oxidant challenge. This study provides insight into the mechanisms by which dimethyl fumarate could preserve myelin integrity in patients with multiple sclerosis. PMID:25967672

  3. Prolonged Subdural Infusion of Kynurenic Acid Is Associated with Dose-Dependent Myelin Damage in the Rat Spinal Cord

    PubMed Central

    Dabrowski, Wojciech; Kwiecien, Jacek M.; Rola, Radoslaw; Klapec, Michal; Stanisz, Greg J.; Kotlinska-Hasiec, Edyta; Oakden, Wendy; Janik, Rafal; Coote, Margaret; Frey, Benicio N.; Turski, Waldemar A.

    2015-01-01

    Background Kynurenic acid (KYNA) is the end stage metabolite of tryptophan produced mainly by astrocytes in the central nervous system (CNS). It has neuroprotective activities but can be elevated in the neuropsychiatric disorders. Toxic effects of KYNA in the CNS are unknown. The aim of this study was to assess the effect of the subdural KYNA infusion on the spinal cord in adult rats. Methods A total of 42 healthy adult rats were randomly assigned into six groups and were infused for 7 days with PBS (control) or 0.0002 pmol/min, 0.01 nmol/min, 0.1 nmol/min, 1 nmol/min, and 10 nmol/min of KYNA per 7 days. The effect of KYNA on spinal cord was determined using histological and electron microscopy examination. Myelin oligodendrocyte glycoprotein (MOG) was measured in the blood serum to assess a degree of myelin damage. Result In all rats continuous long-lasting subdural KYNA infusion was associated with myelin damage and myelin loss that was increasingly widespread in a dose-depended fashion in peripheral, sub-pial areas. Damage to myelin sheaths was uniquely related to the separation of lamellae at the intraperiod line. The damaged myelin sheaths and areas with complete loss of myelin were associated with limited loss of scattered axons while vast majority of axons in affected areas were morphologically intact. The myelin loss-causing effect of KYNA occurred with no necrosis of oligodendrocytes, with locally severe astrogliosis and no cellular inflammatory response. Additionally, subdural KYNA infusion increased blood MOG concentration. Moreover, the rats infused with the highest doses of KYNA (1 and 10 nmol/min) demonstrated adverse neurological signs including weakness and quadriplegia. Conclusions We suggest, that subdural infusion of high dose of KYNA can be used as an experimental tool for the study of mechanisms of myelin damage and regeneration. On the other hand, the administration of low, physiologically relevant doses of KYNA may help to discover the role

  4. Temporal and spatial expression of major myelin proteins in the human fetal spinal cord during the second trimester

    SciTech Connect

    Weidenheim, K.M.; Bodhireddy, S.R.; Rashbaum, W.K.; Lyman, W.D.

    1996-06-01

    Immunohistochemical identification of myelin basic protein (MBP) is a sensitive method for assessing myelination in the human fetal central nervous system (CNS). However, the temporospatial relationship of expression of two other major myelin proteins, proteolipid protein (PLP) and myelin-associated glycoprotein (MAG) to that of MBP during fetal development has not been assessed in human tissues. Vibratome sections of cervical, thoracic and lumbosacral levels from 37 normal spinal cords of {le} 10 to 24 gestational week (GW) fetuses were analyzed using immunohistochemical methods. Using light microscopy, MBP was the first oligodendrocyte marker detected, present by 10 GW at more rostral levels. PLP and MAG were detected rostrally between 12 to 14 GW. All myelin proteins were expressed in anterior to posterior and rostral to caudal gradients. By the late second trimester, expression of MBP, PLP and MAG was noted in all locations in the spinal white matter except for the corticospinal tract. Expression of MAG was particularly marked in the posterior root entry zone and propriospinal tracts. The results suggest that PLP and MAG are expressed later than MBP but follow similar spatial gradients. 44 refs., 11 figs., 2 tabs.

  5. Nonsynaptic junctions on myelinating glia promote preferential myelination of electrically active axons

    PubMed Central

    Wake, Hiroaki; Ortiz, Fernando C.; Woo, Dong Ho; Lee, Philip R.; Angulo, María Cecilia; Fields, R. Douglas

    2015-01-01

    The myelin sheath on vertebrate axons is critical for neural impulse transmission, but whether electrically active axons are preferentially myelinated by glial cells, and if so, whether axo-glial synapses are involved, are long-standing questions of significance to nervous system development, plasticity and disease. Here we show using an in vitro system that oligodendrocytes preferentially myelinate electrically active axons, but synapses from axons onto myelin-forming oligodendroglial cells are not required. Instead, vesicular release at nonsynaptic axo-glial junctions induces myelination. Axons releasing neurotransmitter from vesicles that accumulate in axon varicosities induces a local rise in cytoplasmic calcium in glial cell processes at these nonsynaptic functional junctions, and this signalling stimulates local translation of myelin basic protein to initiate myelination. PMID:26238238

  6. Auraptene induces oligodendrocyte lineage precursor cells in a cuprizone-induced animal model of demyelination.

    PubMed

    Nakajima, Mitsunari; Shimizu, Risei; Furuta, Kohei; Sugino, Mami; Watanabe, Takashi; Aoki, Rui; Okuyama, Satoshi; Furukawa, Yoshiko

    2016-05-15

    We investigated the effects of auraptene on mouse oligodendroglial cell lineage in an animal model of demyelination induced by cuprizone. Auraptene, a citrus coumarin, was intraperitoneally administered to mice fed the demyelinating agent cuprizone. Immunohistochemical analysis of the corpus callosum and/or Western blotting analysis of brain extracts revealed that cuprizone reduced immunoreactivity for myelin-basic protein, a marker of myelin, whereas it increased immunoreactivity to platelet derived-growth factor receptor-α, a marker of oligodendrocyte precursor cells. Administration of auraptene enhanced the immunoreactivity to oligodendrocyte transcription factor 2, a marker of oligodendrocyte precursor cells and oligodendrocyte lineage precursor cells, but had no effect on immunoreactivity to myelin-basic protein or platelet-derived growth factor receptor-α. These findings suggest that auraptene promotes the production of oligodendrocyte lineage precursor cells in an animal model of demyelination and may be useful for individuals with demyelinating diseases. PMID:26944297

  7. The influence of glutamatergic receptor antagonists on biochemical and ultrastructural changes in myelin membranes of rats subjected to experimental autoimmune encephalomyelitis.

    PubMed

    Dąbrowska-Bouta, Beata; Strużyńska, Lidia; Chalimoniuk, Małgorzata; Frontczak-Baniewicz, Małgorzata; Sulkowski, Grzegorz

    2015-01-01

    Elevated extracellular glutamate in the synaptic cleft causes overactivation of glutamate receptors and kills neurons by an excitotoxic mechanism. Recent studies have shown that glutamate can also lead to toxic injury of white matter oligodendrocytes in myelin sheaths and consequently to axon demyelination. The present study was performed using the rodent model of multiple sclerosis known as experimental autoimmune encephalomyelitis (EAE). The aim of the study was to test the effects of the glutamatergic receptor antagonists amantadine and memantine (antagonists of NMDA receptors), LY 367384 (an antagonist of mGluR1), and MPEP (an mGluR5 antagonist) on the development of neurological symptoms in immunized animals, morphological changes in cerebral myelin, and expression of mRNA of the principal myelin proteins PLP, MBP, MOG, MAG, and CNPase. Pharmacological inhibition of NMDA receptors by amantadine and memantine was found to suppress neurological symptoms in EAE rats, whereas antagonists of the group I metabotropic glutamate receptors (mGluRs G I) did not function positively. In the symptomatic phase of the disease we observed destruction of myelin sheaths via electron microscopy and decreased levels of mRNA for all of the principal myelin proteins. The results reveal that glutamate receptor antagonists have a positive effect on the expression of mRNA MBP and glycoproteins MAG and MOG but not on myelin ultrastructure. PMID:26785366

  8. Subtype-specific oligodendrocyte dynamics in organotypic culture.

    PubMed

    Haber, Michael; Vautrin, Sandrine; Fry, Elizabeth J; Murai, Keith K

    2009-07-01

    The morphogenesis of oligodendrocytes is essential for central nervous system myelin formation and the rapid propagation of axon potentials through saltatory conduction. However, the discrete cellular events involved in the three-dimensional maturation of oligodendrocytes remain to be fully described. To address this, we followed the developmental stages of oligodendrocytes in mouse organotypic hippocampal slice cultures for 7-60 days using viral-mediated gene delivery of membrane-targeted fluorescent proteins. Using static and time-lapse confocal imaging, we find that postmigratory NG2-expressing cells exhibit slow anatomical reorganization over the course of hours. This is in direct contrast to oligodendrocytes that take on a promyelinating and transitional phenotype, which display a more complex morphology and undergo dramatic actin-dependent structural remodeling over just minutes. More mature myelinating oligodendrocytes, which have pruned most of their processes, still retain some local remodeling behavior at developing internodes, but in general, revert to a relatively stable state. Our findings provide a detailed characterization of cellular events that help shape oligodendrocyte morphology and likely participate in neuron-glial cell interactions and the process of myelination. PMID:19115396

  9. The role of oligodendrocytes and oligodendrocyte progenitors in CNS remyelination.

    PubMed

    Keirstead, H S; Blakemore, W F

    1999-01-01

    Remyelination enables restoration of saltatory conduction and a return of normal function lost during demyelination. Unfortunately, remyelination is often incomplete in the adult human central nervous system (CNS) and this failure of remyelination is one of the main reasons for clinical deficits in demyelinating disease. An understanding of the failure of remyelination in demyelinating diseases such as Multiple Sclerosis depends upon the elucidation of cellular events underlying successful remyelination. Although the potential for remyelination of the adult CNS has been well established, there is still some dispute regarding the origin of the remyelinating cell population. The literature variously reports that remyelinating oligodendrocytes arise from dedifferentiation and/or proliferation of mature oligodendrocytes, or are generated solely from proliferation and differentiation of glial progenitor cells. This review focuses on studies carried out on remyelinating lesions in the adult rat spinal cord produced by injection of antibodies to galactocerebroside plus serum complement that demonstrate: 1) oligodendrocytes which survive within an area of demyelination do not contribute to remyelination, 2) remyelination is carried out by oligodendrocyte progenitor cells, 3) recruitment of oligodendrocyte progenitors to an area of demyelination is a local response, and 4) division of oligodendrocyte progenitors is symmetrical and results in chronic depletion of the oligodendrocyte progenitor population in the normal white matter around an area of remyelination. These results suggest that failure of remyelination may be contributed to by a depletion of oligodendrocyte progenitors especially following repeated episodes of demyelination. Remyelination allows the return of saltatory conduction (Smith et al., 1979) and the functional recovery of demyelination-induced deficits (Jeffery et al., 1997). Findings such as these have encouraged research aimed at enhancing the limited

  10. Cyclic AMP and Polyamines Overcome Inhibition by Myelin-Associated Glycoprotein through eIF5A-Mediated Increases in p35 Expression and Activation of Cdk5.

    PubMed

    He, Huifang; Deng, Kangwen; Siddiq, Mustafa M; Pyie, Aung; Mellado, Wilfredo; Hannila, Sari S; Filbin, Marie T

    2016-03-01

    Inhibitory molecules associated with CNS myelin, such as myelin-associated glycoprotein (MAG), represent major obstacles to axonal regeneration following CNS injury. Our laboratory has shown that elevating levels of intracellular cAMP, via application of the nonhydrolyzable analog dibutyryl cAMP (dbcAMP), can block the inhibitory effects of MAG and myelin. We have also shown that elevation of cAMP results in upregulation of arginase I and increased polyamine synthesis. Treatment with putrescine or spermidine blocks myelin-mediated inhibition of neurite outgrowth, but the mechanism underlying this effect has not yet been elucidated. Here we show that cyclin-dependent kinase 5 (Cdk5) is required for dbcAMP and putrescine to overcome MAG-mediated inhibition. The ability of dbcAMP and putrescine to overcome inhibition by MAG is abolished in the presence of roscovitine, a Cdk inhibitor that has greater selectivity for Cdk5, and expression of dominant negative Cdk5 abolishes the ability of dbcAMP or putrescine to enhance neurite outgrowth in the presence of MAG. Importantly, dbcAMP and putrescine increase expression of p35, the neuron-specific activator of Cdk5, and rat DRG neurons transduced with HSV overexpressing p35 can overcome inhibition by MAG. The upregulation of p35 by putrescine is also reflected in increased localization of p35 to neurites and growth cones. Last, we show that putrescine upregulates p35 expression by serving as a substrate for hypusine modification of eIF5A, and that this hypusination is necessary for putrescine's ability to overcome inhibition by MAG. Our findings reveal a previously unknown mechanism by which polyamines may encourage regeneration after CNS injury. PMID:26961960

  11. Reduced Myelin Basic Protein and Actin-Related Gene Expression in Visual Cortex in Schizophrenia

    PubMed Central

    Matthews, Paul R.; Eastwood, Sharon L.; Harrison, Paul J.

    2012-01-01

    Most brain gene expression studies of schizophrenia have been conducted in the frontal cortex or hippocampus. The extent to which alterations occur in other cortical regions is not well established. We investigated primary visual cortex (Brodmann area 17) from the Stanley Neuropathology Consortium collection of tissue from 60 subjects with schizophrenia, bipolar disorder, major depression, or controls. We first carried out a preliminary array screen of pooled RNA, and then used RT-PCR to quantify five mRNAs which the array identified as differentially expressed in schizophrenia (myelin basic protein [MBP], myelin-oligodendrocyte glycoprotein [MOG], β-actin [ACTB], thymosin β-10 [TB10], and superior cervical ganglion-10 [SCG10]). Reduced mRNA levels were confirmed by RT-PCR for MBP, ACTB and TB10. The MBP reduction was limited to transcripts containing exon 2. ACTB and TB10 mRNAs were also decreased in bipolar disorder. None of the transcripts were altered in subjects with major depression. Reduced MBP mRNA in schizophrenia replicates findings in other brain regions and is consistent with oligodendrocyte involvement in the disorder. The decreases in expression of ACTB, and the actin-binding protein gene TB10, suggest changes in cytoskeletal organisation. The findings confirm that the primary visual cortex shows molecular alterations in schizophrenia and extend the evidence for a widespread, rather than focal, cortical pathophysiology. PMID:22675524

  12. Functional organization of an Mbp enhancer exposes striking transcriptional regulatory diversity within myelinating glia.

    PubMed

    Dionne, Nancy; Dib, Samar; Finsen, Bente; Denarier, Eric; Kuhlmann, Tanja; Drouin, Régen; Kokoeva, Maia; Hudson, Thomas J; Siminovitch, Kathy; Friedman, Hana C; Peterson, Alan C

    2016-01-01

    In mammals, large caliber axons are ensheathed by myelin, a glial specialization supporting axon integrity and conferring accelerated and energy-efficient action potential conduction. Myelin basic protein (MBP) is required for normal myelin elaboration with maximal mbp transcription in oligodendrocytes requiring the upstream M3 enhancer. To further characterize the mechanism regulating mbp transcription, we defined M3 structure/function relationships by evaluating its evolutionary conservation, DNA footprints and the developmental programing conferred in mice by M3 derivatives. Multiple M3 regulatory element combinations were found to drive expression in oligodendrocytes and Schwann cells with a minimal 129 bp sequence conferring expression in oligodendrocytes throughout myelin elaboration, maintenance and repair. Unexpectedly, M3 derivatives conferred markedly different spatial and temporal expression programs thus illuminating striking transcriptional heterogeneity within post-mitotic oligodendrocytes. Finally, one M3 derivative engaged only during primary myelination, not during adult remyelination, demonstrating that transcriptional regulation in the two states is not equivalent. PMID:26507463

  13. Cross-Reactive Myelin Antibody Induces Renal Disease

    PubMed Central

    Peterson, Lisa K.; Masaki, Takahisa; Wheelwright, Steven R.; Tsunoda, Ikuo; Fujinami, Robert S.

    2011-01-01

    Experimental autoimmune encephalomyelitis (EAE) is an autoimmune model for multiple sclerosis (MS). Previously, we reported renal immunoglobulin (Ig) deposition in mice with myelin oligodendrocyte glycoprotein (MOG92-106) induced progressive-EAE and naïve mice injected with MOG92-106 hybridoma cells producing antibody that cross-reacts with various autoantigens including double-stranded DNA. To assess whether MOG92-106 antibodies actually induce kidney changes, the extent of renal Ig deposition and changes in glomerular histology and filtration were investigated. Mice with progressive-EAE exhibited Ig deposition, glomerular hypercellularity and proteinuria indicating kidney dysfunction. MOG92-106 hybridoma cell injected mice also had Ig in the kidneys and proteinuria. Therefore, sensitization with MOG92-106 and transfer of MOG92-106 antibodies can induce both central nervous system and renal pathology. The renal involvement reported in MS is believed to occur as a side effect of nephrotoxic drugs or neurogenic bladder. Our results demonstrate that an autoimmune response against myelin could induce pathologic changes in the kidney and may help explain renal changes reported in patients with progressive MS. PMID:18608179

  14. Transplantation of mesenchymal stem cells promotes the functional recovery of the central nervous system following cerebral ischemia by inhibiting myelin-associated inhibitor expression and neural apoptosis

    PubMed Central

    FENG, NIANPING; HAO, GUANG; YANG, FENGGANG; QU, FUJUN; ZHENG, HAIHONG; LIANG, SONGLAN; JIN, YONGHUA

    2016-01-01

    Cerebral ischemia, which may lead to cerebral hypoxia and damage of the brain tissue, is a leading cause of human mortality and adult disability. Mesenchymal stem cells (MSCs) are a class of adult progenitor cells with the ability to differentiate into multiple cell types. The transplantation of bone marrow-derived MSCs is a potential therapeutic strategy for cerebral ischemia. However, the underlying mechanism has yet to be elucidated. In the present study, primary MSCs were isolated from healthy rats, labeled and transplanted into the brains of middle cerebral artery occlusion rat models. The location of the labeled MSCs in the rat brains were determined by fluorescent microscopy, and the neurological functions of the rats were scored. Immunohistochemical analyses demonstrated that the protein expression levels of myelin-associated inhibitors of regeneration, including Nogo-A, oligodendrocyte myelin glycoprotein and myelin-associated glycoprotein, were decreased following transplantation of the bone marrow-derived MSCs. Furthermore, the mRNA expression levels of Capase-3 and B-cell lymphoma 2, as determined by reverse transcription-quantitative polymerase chain reactions, were downregulated and upregulated, respectively, in the MSC-transplanted rats; thus suggesting that neural apoptosis was inhibited. The results of the present study suggested that the transplantation of bone marrow-derived MSCs was able to promote the functional recovery of the central nervous system following cerebral ischemia. Accordingly, inhibitors targeting myelin-associated inhibitors and apoptosis may be of clinical significance for cerebral ischemia in the future. PMID:27168778

  15. CNS Myelination Requires Cytoplasmic Dynein Function

    PubMed Central

    Yang, Michele L.; Shin, Jimann; Kearns, Christina A.; Langworthy, Melissa M.; Snell, Heather; Walker, Macie B.; Appel, Bruce

    2014-01-01

    Background Cytoplasmic dynein provides the main motor force for minus-end-directed transport of cargo on microtubules. Within the vertebrate central nervous system (CNS), proliferation, neuronal migration and retrograde axon transport are among the cellular functions known to require dynein. Accordingly, mutations of DYNC1H1, which encodes the heavy chain subunit of cytoplasmic dynein, have been linked to developmental brain malformations and axonal pathologies. Oligodendrocytes, the myelinating glial cell type of the CNS, migrate from their origins to their target axons and subsequently extend multiple long processes that ensheath axons with specialized insulating membrane. These processes are filled with microtubules, which facilitate molecular transport of myelin components. However, whether oligodendrocytes require cytoplasmic dynein to ensheath axons with myelin is not known. Results We identified a mutation of zebrafish dync1h1 in a forward genetic screen that caused a deficit of oligodendrocytes. Using in vivo imaging and gene expression analyses, we additionally found evidence that dync1h1 promotes axon ensheathment and myelin gene expression. Conclusions In addition to its well known roles in axon transport and neuronal migration, cytoplasmic dynein contributes to neural development by promoting myelination. PMID:25488883

  16. Motor skill learning requires active central myelination.

    PubMed

    McKenzie, Ian A; Ohayon, David; Li, Huiliang; de Faria, Joana Paes; Emery, Ben; Tohyama, Koujiro; Richardson, William D

    2014-10-17

    Myelin-forming oligodendrocytes (OLs) are formed continuously in the healthy adult brain. In this work, we study the function of these late-forming cells and the myelin they produce. Learning a new motor skill (such as juggling) alters the structure of the brain's white matter, which contains many OLs, suggesting that late-born OLs might contribute to motor learning. Consistent with this idea, we show that production of newly formed OLs is briefly accelerated in mice that learn a new skill (running on a "complex wheel" with irregularly spaced rungs). By genetically manipulating the transcription factor myelin regulatory factor in OL precursors, we blocked production of new OLs during adulthood without affecting preexisting OLs or myelin. This prevented the mice from mastering the complex wheel. Thus, generation of new OLs and myelin is important for learning motor skills. PMID:25324381

  17. Disruption of Cnp1 uncouples oligodendroglial functions in axonal support and myelination.

    PubMed

    Lappe-Siefke, Corinna; Goebbels, Sandra; Gravel, Michel; Nicksch, Eva; Lee, John; Braun, Peter E; Griffiths, Ian R; Nave, Klaus-Armin

    2003-03-01

    Myelination of axons by oligodendrocytes enables rapid impulse propagation in the central nervous system. But long-term interactions between axons and their myelin sheaths are poorly understood. Here we show that Cnp1, which encodes 2',3'-cyclic nucleotide phosphodiesterase in oligodendrocytes, is essential for axonal survival but not for myelin assembly. In the absence of glial cyclic nucleotide phosphodiesterase, mice developed axonal swellings and neurodegeneration throughout the brain, leading to hydrocephalus and premature death. But, in contrast to previously studied myelin mutants, the ultrastructure, periodicity and physical stability of myelin were not altered in these mice. Genetically, the chief function of glia in supporting axonal integrity can thus be completely uncoupled from its function in maintaining compact myelin. Oligodendrocyte dysfunction, such as that in multiple sclerosis lesions, may suffice to cause secondary axonal loss. PMID:12590258

  18. Functional Delay of Myelination of Auditory Delay Lines in the Nucleus Laminaris of the Barn Owl

    PubMed Central

    Cheng, Shih-Min; Carr, Catherine E.

    2012-01-01

    In the barn owl, maps of interaural time difference (ITD) are created in the nucleus laminaris (NL) by interdigitating axons that act as delay lines. Adult delay line axons are myelinated, and this myelination is timely, coinciding with the attainment of adult head size, and stable ITD cues. The proximal portions of the axons become myelinated in late embryonic life, but the delay line portions of the axon in NL remain unmyelinated until the first postnatal week. Myelination of the delay lines peaks at the third week posthatch, and myelinating oligodendrocyte density approaches adult levels by one month, when the head reaches its adult width. Migration of oligodendrocyte progenitors into NL and the subsequent onset of myelination may be restricted by a glial barrier in late embryonic stages and the first posthatch week, since the loss of tenascin-C immunoreactivity in NL is correlated with oligodendrocyte progenitor migration into NL. PMID:17918244

  19. Neuronal Activity Promotes Oligodendrogenesis and Adaptive Myelination in the Mammalian Brain

    PubMed Central

    Gibson, Erin M.; Purger, David; Mount, Christopher W.; Goldstein, Andrea K.; Lin, Grant L.; Wood, Lauren S.; Inema, Ingrid; Miller, Sarah E.; Bieri, Gregor; Zuchero, J. Bradley; Barres, Ben A.; Woo, Pamelyn J.; Vogel, Hannes; Monje, Michelle

    2014-01-01

    Myelination of the central nervous system requires the generation of functionally mature oligodendrocytes from oligodendrocyte precursor cells (OPCs). Electrically active neurons may influence OPC function and selectively instruct myelination of an active neural circuit. In this work, we use optogenetic stimulation of the premotor cortex in awake, behaving mice to demonstrate that neuronal activity elicits a mitogenic response of neural progenitor cells and OPCs, promotes oligodendrogenesis, and increases myelination within the deep layers of the premotor cortex and subcortical white matter. We further show that this neuronal activity–regulated oligodendrogenesis and myelination is associated with improved motor function of the corresponding limb. Oligodendrogenesis and myelination appear necessary for the observed functional improvement, as epigenetic blockade of oligodendrocyte differentiation and myelin changes prevents the activity-regulated behavioral improvement. PMID:24727982

  20. Nitric oxide targets oligodendrocytes and promotes their morphological differentiation

    PubMed Central

    Garthwaite, Giti; Hampden-Smith, Kathryn; Wilson, Gary W; Goodwin, David A; Garthwaite, John

    2015-01-01

    In the central nervous system, nitric oxide (NO) transmits signals from one neurone to another, or from neurones to astrocytes or blood vessels, but the possibility of oligodendrocytes being physiological NO targets has been largely ignored. By exploiting immunocytochemistry for cGMP, the second messenger generated on activation of NO receptors, oligodendrocytes were found to respond to both exogenous and endogenous NO in cerebellar slices from rats aged 8 days to adulthood. Atrial natriuretic peptide, which acts on membrane-associated guanylyl cyclase-coupled receptors, also raised oligodendrocyte cGMP in cerebellar slices. The main endogenous source of NO accessing oligodendrocytes appeared to be the neuronal NO synthase isoform, which was active even under basal conditions and in a manner that was independent of glutamate receptors. Oligodendrocytes in brainstem slices were also shown to be potential NO targets. In contrast, in the optic nerve, oligodendrocyte cGMP was raised by natriuretic peptides but not NO. When cultures of cerebral cortex were continuously exposed to low NO concentrations (estimated as 40–90 pM), oligodendrocytes responded with a striking increase in arborization. This stimulation of oligodendrocyte growth could be replicated by low concentrations of 8-bromo-cGMP (maximum effect at 1 µM). It is concluded that oligodendrocytes are probably widespread targets for physiological NO (or natriuretic peptide) signals, with the resulting rise in cGMP serving to enhance their growth and maturation. NO might help coordinate the myelination of axons to the ongoing level of neuronal activity during development and could potentially contribute to adaptive changes in myelination in the adult. PMID:25327839

  1. Olig1 Function Is Required for Oligodendrocyte Differentiation in the Mouse Brain

    PubMed Central

    Dai, Jinxiang; Bercury, Kathryn K.; Ahrendsen, Jared T.

    2015-01-01

    Oligodendrocyte differentiation and myelination are tightly regulated processes orchestrated by a complex transcriptional network. Two bHLH transcription factors in this network, Olig1 and Olig2, are expressed exclusively by oligodendrocytes after late embryonic development. Although the role of Olig2 in the lineage is well established, the role of Olig1 is still unclear. The current studies analyzed the function of Olig1 in oligodendrocyte differentiation and developmental myelination in brain. Both oligodendrocyte progenitor cell commitment and oligodendrocyte differentiation were impaired in the corpus callosum of Olig1-null mice, resulting in hypomyelination throughout adulthood in the brain. As seen in previous studies with this mouse line, although there was an early myelination deficit in the spinal cord, essentially full recovery with normal spinal cord myelination was seen. Intriguingly, this regional difference may be partially attributed to compensatory upregulation of Olig2 protein expression in the spinal cord after Olig1 deletion, which is not seen in brain. The current study demonstrates a unique role for Olig1 in promoting oligodendrocyte progenitor cell commitment, differentiation, and subsequent myelination primarily in brain, but not spinal cord. PMID:25762682

  2. Olig1 function is required for oligodendrocyte differentiation in the mouse brain.

    PubMed

    Dai, Jinxiang; Bercury, Kathryn K; Ahrendsen, Jared T; Macklin, Wendy B

    2015-03-11

    Oligodendrocyte differentiation and myelination are tightly regulated processes orchestrated by a complex transcriptional network. Two bHLH transcription factors in this network, Olig1 and Olig2, are expressed exclusively by oligodendrocytes after late embryonic development. Although the role of Olig2 in the lineage is well established, the role of Olig1 is still unclear. The current studies analyzed the function of Olig1 in oligodendrocyte differentiation and developmental myelination in brain. Both oligodendrocyte progenitor cell commitment and oligodendrocyte differentiation were impaired in the corpus callosum of Olig1-null mice, resulting in hypomyelination throughout adulthood in the brain. As seen in previous studies with this mouse line, although there was an early myelination deficit in the spinal cord, essentially full recovery with normal spinal cord myelination was seen. Intriguingly, this regional difference may be partially attributed to compensatory upregulation of Olig2 protein expression in the spinal cord after Olig1 deletion, which is not seen in brain. The current study demonstrates a unique role for Olig1 in promoting oligodendrocyte progenitor cell commitment, differentiation, and subsequent myelination primarily in brain, but not spinal cord. PMID:25762682

  3. Remyelination by Resident Oligodendrocyte Precursor Cells in a Xenopus laevis Inducible Model of Demyelination.

    PubMed

    Sekizar, Sowmya; Mannioui, Abdelkrim; Azoyan, Loris; Colin, Catherine; Thomas, Jean-Léon; Du Pasquier, David; Mallat, Michel; Zalc, Bernard

    2015-01-01

    We have generated a Xenopus laevis transgenic line, MBP-GFP-NTR, allowing conditional ablation of myelin-forming oligodendrocytes. In this transgenic line the transgene is driven by the proximal portion of the myelin basic protein regulatory sequence, specific to mature oligodendrocytes. The transgene protein is formed by the green fluorescent protein reporter fused to the Escherichia coli nitroreductase (NTR) selection enzyme. The NTR enzyme converts the innocuous prodrug metronidazole (MTZ) to a cytotoxin. Ablation of oligodendrocytes by MTZ treatment of the tadpole induced demyelination, and here we show that myelin debris are subsequently eliminated by microglial cells. After cessation of MTZ treatment, remyelination proceeded spontaneously. We questioned the origin of remyelinating cells. Our data suggest that Sox10+ oligodendrocyte precursor cells (OPCs), which are already present in the optic nerve prior to the experimentally induced demyelination, are responsible for remyelination, and this required only minimal (if any) cell division of OPCs. © 2015 S. Karger AG, Basel. PMID:25896276

  4. Fbxw7 Limits Myelination by Inhibiting mTOR Signaling

    PubMed Central

    Kearns, Christina A.; Ravanelli, Andrew M.; Cooper, Kirsten

    2015-01-01

    An important characteristic of vertebrate CNS development is the formation of specific amounts of insulating myelin membrane on axons. CNS myelin is produced by oligodendrocytes, glial cells that extend multiple membrane processes to wrap multiple axons. Recent data have shown that signaling mediated by the mechanistic target of rapamycin (mTOR) serine/threonine kinase promotes myelination, but factors that regulate mTOR activity for myelination remain poorly defined. Through a forward genetic screen in zebrafish, we discovered that mutation of fbxw7, which encodes the substrate recognition subunit of a SCF ubiquitin ligase that targets proteins for degradation, causes hypermyelination. Among known Fbxw7 targets is mTOR. Here, we provide evidence that mTOR signaling activity is elevated in oligodendrocyte lineage cells of fbxw7 mutant zebrafish larvae. Both genetic and pharmacological inhibition of mTOR function suppressed the excess myelin gene expression resulting from loss of Fbxw7 function, indicating that mTOR is a functionally relevant target of Fbxw7 in oligodendrocytes. fbxw7 mutant larvae wrapped axons with more myelin membrane than wild-type larvae and oligodendrocyte-specific expression of dominant-negative Fbxw7 produced longer myelin sheaths. Our data indicate that Fbxw7 limits the myelin-promoting activity of mTOR, thereby serving as an important brake on developmental myelination. SIGNIFICANCE STATEMENT Myelin, a specialized, proteolipid-rich membrane that ensheaths and insulates nerve fibers, facilitates the rapid conduction of electrical impulses over long distances. Abnormalities in myelin formation or maintenance result in intellectual and motor disabilities, raising a need for therapeutic strategies designed to promote myelination. The mTOR kinase is a powerful driver of myelination, but the mechanisms that regulate mTOR function in myelination are not well understood. Our studies reveal that Fbxw7, a subunit of a ubiquitin ligase that targets

  5. [Development and regeneration of oligodendrocytes: therapeutic perspectives in demyelinating diseases].

    PubMed

    Dubois-Dalcq, M

    2005-01-01

    The function of the central nervous system (CNS) is in great part depending on glial cells as, for instance, radial glial cells give rise to cortical neurons, and oligodendrocytes synthesize an immense specialized membrane that enwraps axons to make myelin internodes. Myelin allows fast saltatory conduction of action potentials along myelinated nerve tracts and assures the survival of axons. Oligodendrocytes precursors (OP) emerge during development, first in the spinal cord and later in the telencephalon from multipotential neural precursors in germinative zones around the cerebral ventricles. Morphogens and specific growth factors stimulate the growth, migration and survival of OPs toward axons, culminating in myelination. Such precursors can be isolated from human brain and persist in the adult CNS, allowing some degree of remyelination in the course of a demyelinating disease caused by an infectious agent or inflammation such as multiple sclerosis (MS). These remyelinating cells can recapitulate some molecular events of myelination while new OPs are generated by neural stem cells in the subventricular zones and niches. This natural repair process often decreases with time in man, raising questions about the appropriateness of rodent animal models where remyelination is robust. The challenge today in MS is to develop a pharmacology of myelin repair by endogenous precursors which, if successful, might be more likely to result in clinical benefits than transplantation of myelin-forming cells, shown to be so efficient in rodent models. PMID:16768245

  6. Neurotoxocarosis alters myelin protein gene transcription and expression.

    PubMed

    Heuer, Lea; Beyerbach, Martin; Lühder, Fred; Beineke, Andreas; Strube, Christina

    2015-06-01

    Neurotoxocarosis is an infection of the central nervous system caused by migrating larvae of the common dog and cat roundworms (Toxocara canis and Toxocara cati), which are zoonotic agents. As these parasites are prevalent worldwide and neuropathological and molecular investigations on neurotoxocarosis are scare, this study aims to characterise nerve fibre demyelination associated with neurotoxocarosis on a molecular level. Transcription of eight myelin-associated genes (Cnp, Mag, Mbp, Mog, Mrf-1, Nogo-A, Plp1, Olig2) was determined in the mouse model during six time points of the chronic phase of infection using qRT-PCR. Expression of selected proteins was analysed by Western blotting or immunohistochemistry. Additionally, demyelination and neuronal damage were investigated histologically. Significant differences (p ≤ 0.05) between transcription rates of T. canis-infected and uninfected control mice were detected for all analysed genes while T. cati affected five of eight investigated genes. Interestingly, 2', 3 ´-cyclic nucleotide 3'-phosphodiesterase (Cnp) and myelin oligodendrocyte glycoprotein (Mog) were upregulated in both T. canis- and T. cati-infected mice preceding demyelination. Later, CNPase expression was additionally enhanced. As expected, myelin basic protein (Mbp) was downregulated in cerebra and cerebella of T. canis-infected mice when severe demyelination was present 120 days post infectionem (dpi). The transcriptional pattern observed in the present study appears to reflect direct traumatic and hypoxic effects of larval migration as well as secondary processes including host immune reactions, demyelination and attempts to remyelinate damaged areas. PMID:25773181

  7. MOBP levels are regulated by Fyn kinase and affect the morphological differentiation of oligodendrocytes.

    PubMed

    Schäfer, Isabelle; Müller, Christina; Luhmann, Heiko J; White, Robin

    2016-03-01

    Oligodendrocytes are the myelinating glial cells of the central nervous system (CNS). Myelin is formed by extensive wrapping of oligodendroglial processes around axonal segments, which ultimately allows a rapid saltatory conduction of action potentials within the CNS and sustains neuronal health. The non-receptor tyrosine kinase Fyn is an important signaling molecule in oligodendrocytes. It controls the morphological differentiation of oligodendrocytes and is an integrator of axon-glial signaling cascades leading to localized synthesis of myelin basic protein (MBP), which is essential for myelin formation. The abundant myelin-associated oligodendrocytic basic protein (MOBP) resembles MBP in several aspects and has also been reported to be localized as mRNA and translated in the peripheral myelin compartment. The signals initiating local MOBP synthesis are so far unknown and the cellular function of MOBP remains elusive. Here, we show, by several approaches in cultured primary oligodendrocytes, that MOBP synthesis is stimulated by Fyn activity. Moreover, we reveal a new function for MOBP in oligodendroglial morphological differentiation. PMID:26801084

  8. An ultrastructural study on the reactive oligodendrocytes, myeloclasts, and myelophages in transected dog spinal cord.

    PubMed

    Chang, L W; Kao, C C

    1980-01-01

    As early as 1 to 3 hr after cord transection, proliferation of many reactive oligodendrocytes was observed. Bundles of microfilaments and microtubules were observed in those cells that sent out long, complex pseudopodlike processes near the area of injury. These reactive oligodendrocytes may be comparable to Vaughn's multipotential glia cells. Between 1 day and 1 wk, hypertrophy of the oligodendrocytes was observed. These hypertrophied oligodendrocytes also became hyperactive and infiltrated into the axons within the myelin sheath. These infiltrating hyperactive oligodendrocytes had a scanty fibrillary cytoplasm and are believed to correspond to Jakob's "myeloclasts". The infiltration of macrophages into the nerve fibers and myelin sheaths was also observed. These macrophages were found to be very active in phagocytosis and removal of degenerated debris within the nerve fiber and are believed to represent the "myelophages" described by Jakob in 1913. PMID:6107880

  9. Oligodendrocyte Injury and Pathogenesis of HIV-1-Associated Neurocognitive Disorders.

    PubMed

    Liu, Han; Xu, Enquan; Liu, Jianuo; Xiong, Huangui

    2016-01-01

    Oligodendrocytes wrap neuronal axons to form myelin, an insulating sheath which is essential for nervous impulse conduction along axons. Axonal myelination is highly regulated by neuronal and astrocytic signals and the maintenance of myelin sheaths is a very complex process. Oligodendrocyte damage can cause axonal demyelination and neuronal injury, leading to neurological disorders. Demyelination in the cerebrum may produce cognitive impairment in a variety of neurological disorders, including human immunodeficiency virus type one (HIV-1)-associated neurocognitive disorders (HAND). Although the combined antiretroviral therapy has markedly reduced the incidence of HIV-1-associated dementia, a severe form of HAND, milder forms of HAND remain prevalent even when the peripheral viral load is well controlled. HAND manifests as a subcortical dementia with damage in the brain white matter (e.g., corpus callosum), which consists of myelinated axonal fibers. How HIV-1 brain infection causes myelin injury and resultant white matter damage is an interesting area of current HIV research. In this review, we tentatively address recent progress on oligodendrocyte dysregulation and HAND pathogenesis. PMID:27455335

  10. Astrocytes in Oligodendrocyte Lineage Development and White Matter Pathology

    PubMed Central

    Li, Jiasi; Zhang, Lei; Chu, Yongxin; Namaka, Michael; Deng, Benqiang; Kong, Jiming; Bi, Xiaoying

    2016-01-01

    White matter is primarily composed of myelin and myelinated axons. Structural and functional completeness of myelin is critical for the reliable and efficient transmission of information. White matter injury has been associated with the development of many demyelinating diseases. Despite a variety of scientific advances aimed at promoting re-myelination, their benefit has proven at best to be marginal. Research suggests that the failure of the re-myelination process may be the result of an unfavorable microenvironment. Astrocytes, are the most ample and diverse type of glial cells in central nervous system (CNS) which display multiple functions for the cells of the oligodendrocytes lineage. As such, much attention has recently been drawn to astrocyte function in terms of white matter myelin repair. They are different in white matter from those in gray matter in specific regards to development, morphology, location, protein expression and other supportive functions. During the process of demyelination and re-myelination, the functions of astrocytes are dynamic in that they are able to change functions in accordance to different time points, triggers or reactive pathways resulting in vastly different biologic effects. They have pivotal effects on oligodendrocytes and other cell types in the oligodendrocyte lineage by serving as an energy supplier, a participant of immunological and inflammatory functions, a source of trophic factors and iron and a sustainer of homeostasis. Astrocytic impairment has been shown to be directly linked to the development of neuromyelities optica (NMO). In addition, astroctyes have also been implicated in other white matter conditions such as psychiatric disorders and neurodegenerative diseases such as Alzheimer’s disease (AD), multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). Inhibiting specifically detrimental signaling pathways in astrocytes while preserving their beneficial functions may be a promising approach for

  11. Astrocytes in Oligodendrocyte Lineage Development and White Matter Pathology.

    PubMed

    Li, Jiasi; Zhang, Lei; Chu, Yongxin; Namaka, Michael; Deng, Benqiang; Kong, Jiming; Bi, Xiaoying

    2016-01-01

    White matter is primarily composed of myelin and myelinated axons. Structural and functional completeness of myelin is critical for the reliable and efficient transmission of information. White matter injury has been associated with the development of many demyelinating diseases. Despite a variety of scientific advances aimed at promoting re-myelination, their benefit has proven at best to be marginal. Research suggests that the failure of the re-myelination process may be the result of an unfavorable microenvironment. Astrocytes, are the most ample and diverse type of glial cells in central nervous system (CNS) which display multiple functions for the cells of the oligodendrocytes lineage. As such, much attention has recently been drawn to astrocyte function in terms of white matter myelin repair. They are different in white matter from those in gray matter in specific regards to development, morphology, location, protein expression and other supportive functions. During the process of demyelination and re-myelination, the functions of astrocytes are dynamic in that they are able to change functions in accordance to different time points, triggers or reactive pathways resulting in vastly different biologic effects. They have pivotal effects on oligodendrocytes and other cell types in the oligodendrocyte lineage by serving as an energy supplier, a participant of immunological and inflammatory functions, a source of trophic factors and iron and a sustainer of homeostasis. Astrocytic impairment has been shown to be directly linked to the development of neuromyelities optica (NMO). In addition, astroctyes have also been implicated in other white matter conditions such as psychiatric disorders and neurodegenerative diseases such as Alzheimer's disease (AD), multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS). Inhibiting specifically detrimental signaling pathways in astrocytes while preserving their beneficial functions may be a promising approach for

  12. Myelin-associated glycoprotein modulates apoptosis of motoneurons during early postnatal development via NgR/p75NTR receptor-mediated activation of RhoA signaling pathways

    PubMed Central

    Palandri, A; Salvador, V R; Wojnacki, J; Vivinetto, A L; Schnaar, R L; Lopez, P H H

    2015-01-01

    Myelin-associated glycoprotein (MAG) is a minor constituent of nervous system myelin, selectively expressed on the periaxonal myelin wrap. By engaging multiple axonal receptors, including Nogo-receptors (NgRs), MAG exerts a nurturing and protective effect the axons it ensheaths. Pharmacological activation of NgRs has a modulatory role on p75NTR-dependent postnatal apoptosis of motoneurons (MNs). However, it is not clear whether this reflects a physiological role of NgRs in MN development. NgRs are part of a multimeric receptor complex, which includes p75NTR, Lingo-1 and gangliosides. Upon ligand binding, this multimeric complex activates RhoA/ROCK signaling in a p75NTR-dependent manner. The aim of this study was to analyze a possible modulatory role of MAG on MN apoptosis during postnatal development. A time course study showed that Mag-null mice suffer a loss of MNs during the first postnatal week. Also, these mice exhibited increased susceptibility in an animal model of p75NTR-dependent MN apoptosis induced by nerve-crush injury, which was prevented by treatment with a soluble form of MAG (MAG-Fc). The protective role of MAG was confirmed in in vitro models of p75NTR-dependent MN apoptosis using the MN1 cell line and primary cultures. Lentiviral expression of shRNA sequences targeting NgRs on these cells abolished protection by MAG-Fc. Analysis of RhoA activity using a FRET-based RhoA biosensor showed that MAG-Fc activates RhoA. Pharmacological inhibition of p75NTR/RhoA/ROCK pathway, or overexpression of a p75NTR mutant unable to activate RhoA, completely blocked MAG-Fc protection against apoptosis. The role of RhoA/ROCK signaling was further confirmed in the nerve-crush model, where pretreatment with ROCK inhibitor Y-27632 blocked the pro-survival effect of MAG-Fc. These findings identify a new protective role of MAG as a modulator of apoptosis of MNs during postnatal development by a mechanism involving the p75NTR/RhoA/ROCK signaling pathway. Also, our results

  13. Endoplasmic reticulum stress in disorders of myelinating cells

    PubMed Central

    Lin, Wensheng; Popko, Brian

    2009-01-01

    Myelinating cells, oligodendrocytes in the CNS and Schwann cells in the PNS, produce an enormous amount of plasma membrane during the myelination process, making them particularly susceptible to disruptions to the secretory pathway. ER stress, initiated by the accumulation of unfolded or misfolded proteins, activates the unfolded protein response (UPR), which adapts cells to the stress. If this adaptive response is insufficient, the UPR activates an apoptotic program to eliminate the affected cells. Recent observations suggest that ER stress in myelinating cells plays an important role in the pathogenesis of various disorders of myelin, including Charcot-Marie-Tooth disease (CMT), Pelizaeus-Merzbacher disease (PMD), Vanishing White Matter Disease (VWMD), as well as in the most common disorder of myelin, multiples sclerosis (MS). A better understanding of ER stress in myelinating cells has laid the groundwork for the design of novel therapeutic strategies to promote myelinating cell survival in these disorders. PMID:19287390

  14. Review: Glial lineages and myelination in the central nervous system

    PubMed Central

    COMPSTON, ALASTAIR; ZAJICEK, JOHN; SUSSMAN, JON; WEBB, ANNA; HALL, GILLIAN; MUIR, DAVID; SHAW, CHRISTOPHER; WOOD, ANDREW; SCOLDING, NEIL

    1997-01-01

    Oligodendrocytes, derived from stem cell precursors which arise in subventricular zones of the developing central nervous system, have as their specialist role the synthesis and maintenance of myelin. Astrocytes contribute to the cellular architecture of the central nervous system and act as a source of growth factors and cytokines; microglia are bone-marrow derived macrophages which function as primary immunocompetent cells in the central nervous system. Myelination depends on the establishment of stable relationships between each differentiated oligodendrocyte and short segments of several neighbouring axons. There is growing evidence, especially from studies of glial cell implantation, that oligodendrocyte precursors persist in the adult nervous system and provide a limited capacity for the restoration of structure and function in myelinated pathways damaged by injury or disease. PMID:9061442

  15. Systematic Review of Pharmacological Properties of the Oligodendrocyte Lineage

    PubMed Central

    Marinelli, Carla; Bertalot, Thomas; Zusso, Morena; Skaper, Stephen D.; Giusti, Pietro

    2016-01-01

    Oligodendrogenesis and oligodendrocyte precursor maturation are essential processes during the course of central nervous system development, and lead to the myelination of axons. Cells of the oligodendrocyte lineage are generated in the germinal zone from migratory bipolar oligodendrocyte precursor cells (OPCs), and acquire cell surface markers as they mature and respond specifically to factors which regulate proliferation, migration, differentiation, and survival. Loss of myelin underlies a wide range of neurological disorders, some of an autoimmune nature—multiple sclerosis probably being the most prominent. Current therapies are based on the use of immunomodulatory agents which are likely to promote myelin repair (remyelination) indirectly by subverting the inflammatory response, aspects of which impair the differentiation of OPCs. Cells of the oligodendrocyte lineage express and are capable of responding to a diverse array of ligand-receptor pairs, including neurotransmitters and nuclear receptors such as γ-aminobutyric acid, glutamate, adenosine triphosphate, serotonin, acetylcholine, nitric oxide, opioids, prostaglandins, prolactin, and cannabinoids. The intent of this review is to provide the reader with a synopsis of our present state of knowledge concerning the pharmacological properties of the oligodendrocyte lineage, with particular attention to these receptor-ligand (i.e., neurotransmitters and nuclear receptor) interactions that can influence oligodendrocyte migration, proliferation, differentiation, and myelination, and an appraisal of their therapeutic potential. For example, many promising mediators work through Ca2+ signaling, and the balance between Ca2+ influx and efflux can determine the temporal and spatial properties of oligodendrocytes (OLs). Moreover, Ca2+ signaling in OPCs can influence not only differentiation and myelination, but also process extension and migration, as well as cell death in mature mouse OLs. There is also evidence

  16. Oral Administration of Lactococcus lactis Expressing Synthetic Genes of Myelin Antigens in Decreasing Experimental Autoimmune Encephalomyelitis in Rats

    PubMed Central

    Kasarello, Kaja; Kwiatkowska-Patzer, Barbara; Lipkowski, Andrzej W.; Bardowski, Jacek K.; Szczepankowska, Agnieszka K.

    2015-01-01

    Background Multiple sclerosis is a human autoimmunological disease that causes neurodegeneration. One of the potential ways to stop its development is induction of oral tolerance, whose effect lies in decreasing immune response to the fed antigen. It was shown in animal models that administration of specific epitopes of the three main myelin proteins – myelin oligodendrocyte glycoprotein (MOG), myelin basic protein (MBP), and proteolipid protein (PLP) – results in induction of oral tolerance and suppression of disease symptoms. Use of bacterial cells to produce and deliver antigens to gut mucosa seems to be an attractive method for oral tolerance induction in treatment of diseases with autoimmune background. Material/Methods Synthetic genes of MOG35-55, MBP85-97, and PLP139-151 myelin epitopes were generated and cloned in Lactococcus lactis under a CcpA-regulated promoter. The tolerogenic effect of bacterial preparations was tested on experimental autoimmune encephalomyelitis, which is the animal model of MS. EAE was induced in rats by intradermal injection of guinea pig spinal cord homogenate into hind paws. Results Rats were administered preparations containing whole-cell lysates of L. lactis producing myelin antigens using different feeding schemes. Our study demonstrates that 20-fold, but not 4-fold, intragastric administration of autoantigen-expressing L. lactis cells under specific conditions reduces the clinical symptoms of EAE in rats. Conclusions The present study evaluated the use of myelin antigens produced in L. lactis in inhibiting the onset of experimental autoimmune encephalomyelitis in rats. Obtained results indicate that application of such recombinant cells can be an attractive method of oral tolerance induction. PMID:26026273

  17. Simvastatin induces cell death in a mouse cerebellar slice culture (CSC) model of developmental myelination

    PubMed Central

    Xiang, Zhongmin; Reeves, Steven A.

    2009-01-01

    Statins (inhibitors of HMG-CoA reductase) have shown promise in treating multiple sclerosis (MS). However, their effect on oligodendrocyte remyelination of demyelinated axons has not been clarified. Since developmental myelination shares many features with the remyelination process, we investigated the effect of lipophilic simvastatin on developmental myelination in organotypic cerebellar slice cultures (CSC). In this study, we first characterized developmental myelination in CSC from postnatal day (P)5 and P10 mice that express enhanced green fluorescence protein (eGFP) in oligodendrocyte-lineage cells. We then examined the effect of simvastain on three developmental myelination stages: early myelination (P5 CSC, 2DIV), late myelination (P10 CSC, 2DIV) and full myelination (P10 CSC, 10DIV). We found that treatment with simvastatin (0.1 μM) for 6 days decreased the survival of Purkinje cells and oligodendrocytes drastically during the early myelination stage, while moderately during the late and full myelination stages. Oligodendrocytes are more resistant than Purkinje cells. The toxic effect of simvastatin could be rescued by the product of HMG-CoA reductase mevalonate but not low-density lipoprotein (LDL). Additionally, this toxic effect is independent of isoprenylation since farnesyl pyrophosphate (Fpp) but not geranylgeranyl pyrophosphate (GGpp) provided partial rescue. Our findings therefore suggest that inhibition of cholesterol synthesis is detrimental to neuronal tissue. PMID:18929563

  18. Zebrafish as a model to investigate CNS myelination.

    PubMed

    Preston, Marnie A; Macklin, Wendy B

    2015-02-01

    Myelin plays a critical role in proper neuronal function by providing trophic and metabolic support to axons and facilitating energy-efficient saltatory conduction. Myelination is influenced by numerous molecules including growth factors, hormones, transmembrane receptors and extracellular molecules, which activate signaling cascades that drive cellular maturation. Key signaling molecules and downstream signaling cascades controlling myelination have been identified in cell culture systems. However, in vitro systems are not able to faithfully replicate the complex in vivo signaling environment that occurs during development or following injury. Currently, it remains time-consuming and expensive to investigate myelination in vivo in rodents, the most widely used model for studying mammalian myelination. As such, there is a need for alternative in vivo myelination models, particularly ones that can test molecular mechanisms without removing oligodendrocyte lineage cells from their native signaling environment or disrupting intercellular interactions with other cell types present during myelination. Here, we review the ever-increasing role of zebrafish in studies uncovering novel mechanisms controlling vertebrate myelination. These innovative studies range from observations of the behavior of single cells during in vivo myelination as well as mutagenesis- and pharmacology-based screens in whole animals. Additionally, we discuss recent efforts to develop novel models of demyelination and oligodendrocyte cell death in adult zebrafish for the study of cellular behavior in real time during repair and regeneration of damaged nervous systems. PMID:25263121

  19. The acquisition of myelin: a success story.

    PubMed

    Zalc, Bernard

    2006-01-01

    The myelin sheath, and hence the myelin-forming cells (i.e. Schwann cells in the PNS and oligodendrocytes in the CNS), have been a crucial acquisition of vertebrates. The major function of myelin is to increase the velocity of propagation of nerve impulses. Invertebrate axons are ensheathed by glial cells, but do not have a compact myelin. As a consequence, action potentials along invertebrate axons propagate at about 1 m/s, or less. This is sufficient, however, for the survival of small animals (between 0.1 and 30cm). Among invertebrates, only the cephalopods are larger. By increasing their axonal diameter to 1 mm or more, cephalopods have been able to increase the speed of propagation of action potentials and therefore adapt nerve conduction to their larger body size. However, due to the physical constraint imposed by the skull and vertebrae, vertebrates had to find an alternative solution. This was achieved by introducing the myelin sheath, which leads action potentials to propagate at speeds of 50-100m/s without increasing the diameter of their axons. Not all vertebrate axons, however, are myelinated. In the protovertebrates (lancelets, hagfishes, lampreys), which belong to the agnathes (jawless fishes), axons are not ensheathed by myelin. Among living vertebrates, the most ancient myelinated species are the cartilaginous fishes (sharks, rays), suggesting that acquisition of myelin is concomitant with the acquisition of a hinged-jaw, i.e. the gnathostoma. The close association between the apparition of a hinged-jaw and the myelin sheath has led to speculation that among the devonian fishes that have disappeared today, the jawless conodonts and ostracoderms were not myelinated, and that myelin was first acquired by the oldest gnathostomes: the placoderms. I also question where myelin first appeared: the PNS, the CNS or both? I provide evidence that, in fact, it is not the type of myelin-forming cell that is crucial, but the appearance of axonal signals

  20. The control of reactive oxygen species production by SHP-1 in oligodendrocytes.

    PubMed

    Gruber, Ross C; LaRocca, Daria; Minchenberg, Scott B; Christophi, George P; Hudson, Chad A; Ray, Alex K; Shafit-Zagardo, Bridget; Massa, Paul T

    2015-10-01

    We have previously described reduced myelination and corresponding myelin basic protein (MBP) expression in the central nervous system of Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP-1) deficient motheaten (me/me) mice compared with normal littermate controls. Deficiency in myelin and MBP expression in both brains and spinal cords of motheaten mice correlated with reduced MBP mRNA expression levels in vivo and in purified oligodendrocytes in vitro. Therefore, SHP-1 activity seems to be a critical regulator of oligodendrocyte gene expression and function. Consistent with this role, this study demonstrates that oligodendrocytes of motheaten mice and SHP-1-depleted N20.1 cells produce higher levels of reactive oxygen species (ROS) and exhibit corresponding markers of increased oxidative stress. In agreement with these findings, we demonstrate that increased production of ROS coincides with ROS-induced signaling pathways known to affect myelin gene expression in oligodendrocytes. Antioxidant treatment of SHP-1-deficient oligodendrocytes reversed the pathological changes in these cells, with increased myelin protein gene expression and decreased expression of nuclear factor (erythroid-2)-related factor 2 (Nrf2) responsive gene, heme oxygenase-1 (HO-1). Furthermore, we demonstrate that SHP-1 is expressed in human white matter oligodendrocytes, and there is a subset of multiple sclerosis subjects that demonstrate a deficiency of SHP-1 in normal-appearing white matter. These studies reveal critical pathways controlled by SHP-1 in oligodendrocytes that relate to susceptibility of SHP-1-deficient mice to both developmental defects in myelination and to inflammatory demyelinating diseases. PMID:25919645

  1. A selective thyroid hormone β receptor agonist enhances human and rodent oligodendrocyte differentiation.

    PubMed

    Baxi, Emily G; Schott, Jason T; Fairchild, Amanda N; Kirby, Leslie A; Karani, Rabia; Uapinyoying, Prech; Pardo-Villamizar, Carlos; Rothstein, Jeffrey R; Bergles, Dwight E; Calabresi, Peter A

    2014-09-01

    Nerve conduction within the mammalian central nervous system is made efficient by oligodendrocyte-derived myelin. Historically, thyroid hormones have a well described role in regulating oligodendrocyte differentiation and myelination during development; however, it remains unclear which thyroid hormone receptors are required to drive these effects. This is a question with clinical relevance since nonspecific thyroid receptor stimulation can produce deleterious side-effects. Here we report that GC-1, a thyromimetic with selective thyroid receptor β action and a potentially limited side-effect profile, promotes in vitro oligodendrogenesis from both rodent and human oligodendrocyte progenitor cells. In addition, we used in vivo genetic fate tracing of oligodendrocyte progenitor cells via PDGFαR-CreER;Rosa26-eYFP double-transgenic mice to examine the effect of GC-1 on cellular fate and find that treatment with GC-1 during developmental myelination promotes oligodendrogenesis within the corpus callosum, occipital cortex and optic nerve. GC-1 was also observed to enhance the expression of the myelin proteins MBP, CNP and MAG within the same regions. These results indicate that a β receptor selective thyromimetic can enhance oligodendrocyte differentiation in vitro and during developmental myelination in vivo and warrants further study as a therapeutic agent for demyelinating models. PMID:24863526

  2. Schwann cell myelination of the myelin deficient rat spinal cord following X-irradiation

    SciTech Connect

    Duncan, I.D.; Hammang, J.P.; Gilmore, S.A.

    1988-01-01

    The myelin-deficient (md) rat is an X-linked myelin mutant that has an abnormality of oligodendrocytes and a severe paucity of myelin throughout the CNS. This lack of myelin makes it an ideal model in which to study the cellular interactions that occur when foreign myelinating cells are induced in the milieu of this nonmyelinated CNS. In this study, Schwann cells were induced in the lumbosacral spinal cord by exposing it to radiation, a technique demonstrated repeatedly in other nonmutant strains of rats. Md rats and their age-matched littermates were irradiated (3,000 to 4,000 R) at 3 days of age and perfused 16-22 days later after pulse labeling with tritiated thymidine. In the md rat, Schwann cell invasion progressed from the area of the spinal cord-nerve root junction and extended into the dorsal columns and adjacent gray matter. Autoradiographic evidence revealed that many of these cells incorporated 3H-thymidine, indicating that they were undergoing proliferation. Ultrastructural observations showed that there was an integration of these intraspinal Schwann cells with the cells normally occurring in this environment, i.e., oligodendrocytes and astrocytes. The extent of migration and division of Schwann cells, as well as their interactions with glial cells, were similar to those seen in the nonmutant irradiated littermates. These studies provide conclusive evidence that md rat axons are normal with respect to their ability to provide trophic and mitogenic signals to myelinating cells.

  3. The Polarity Protein Scribble Regulates Myelination and Remyelination in the Central Nervous System

    PubMed Central

    Jarjour, Andrew A.; Boyd, Amanda; Dow, Lukas E.; Holloway, Rebecca K.; Goebbels, Sandra; Humbert, Patrick O.; Williams, Anna; ffrench-Constant, Charles

    2015-01-01

    The development and regeneration of myelin by oligodendrocytes, the myelin-forming cells of the central nervous system (CNS), requires profound changes in cell shape that lead to myelin sheath initiation and formation. Here, we demonstrate a requirement for the basal polarity complex protein Scribble in CNS myelination and remyelination. Scribble is expressed throughout oligodendroglial development and is up-regulated in mature oligodendrocytes where it is localised to both developing and mature CNS myelin sheaths. Knockdown of Scribble expression in cultured oligodendroglia results in disrupted morphology and myelination initiation. When Scribble expression is conditionally eliminated in the myelinating glia of transgenic mice, myelin initiation in CNS is disrupted, both during development and following focal demyelination, and longitudinal extension of the myelin sheath is disrupted. At later stages of myelination, Scribble acts to negatively regulate myelin thickness whilst suppressing the extracellular signal-related kinase (ERK)/mitogen-activated protein kinase (MAP) kinase pathway, and localises to non-compact myelin flanking the node of Ranvier where it is required for paranodal axo-glial adhesion. These findings demonstrate an essential role for the evolutionarily-conserved regulators of intracellular polarity in myelination and remyelination. PMID:25807062

  4. The polarity protein Scribble regulates myelination and remyelination in the central nervous system.

    PubMed

    Jarjour, Andrew A; Boyd, Amanda; Dow, Lukas E; Holloway, Rebecca K; Goebbels, Sandra; Humbert, Patrick O; Williams, Anna; ffrench-Constant, Charles

    2015-03-01

    The development and regeneration of myelin by oligodendrocytes, the myelin-forming cells of the central nervous system (CNS), requires profound changes in cell shape that lead to myelin sheath initiation and formation. Here, we demonstrate a requirement for the basal polarity complex protein Scribble in CNS myelination and remyelination. Scribble is expressed throughout oligodendroglial development and is up-regulated in mature oligodendrocytes where it is localised to both developing and mature CNS myelin sheaths. Knockdown of Scribble expression in cultured oligodendroglia results in disrupted morphology and myelination initiation. When Scribble expression is conditionally eliminated in the myelinating glia of transgenic mice, myelin initiation in CNS is disrupted, both during development and following focal demyelination, and longitudinal extension of the myelin sheath is disrupted. At later stages of myelination, Scribble acts to negatively regulate myelin thickness whilst suppressing the extracellular signal-related kinase (ERK)/mitogen-activated protein kinase (MAP) kinase pathway, and localises to non-compact myelin flanking the node of Ranvier where it is required for paranodal axo-glial adhesion. These findings demonstrate an essential role for the evolutionarily-conserved regulators of intracellular polarity in myelination and remyelination. PMID:25807062

  5. Signals that initiate myelination in the developing mammalian nervous system.

    PubMed

    Colello, R J; Pott, U

    1997-08-01

    The myelination of axons by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system is essential for the establishment of saltatory conduction. In the absence or destruction of the myelin sheath, as seen in demyelinating diseases, impulse conduction is impeded resulting in severe sensory and motor deficits. Axon myelination is the culmination of a sequence of events that begins with the differentiation of glial cells and proceeds to the transcription and translation of myelin genes, the elaboration of a myelin sheath, and the recognition and ensheathment of axons. This review examines the regulatory mechanisms for each of these steps and compares and contrasts the role of the axon in initiating myelination in the central and peripheral nervous system. PMID:9396006

  6. Injury and differentiation following inhibition of mitochondrial respiratory chain complex IV in rat oligodendrocytes

    PubMed Central

    Ziabreva, Iryna; Campbell, Graham; Rist, Julia; Zambonin, Jessica; Rorbach, Joanna; Wydro, Mateusz M; Lassmann, Hans; Franklin, Robin J M; Mahad, Don

    2010-01-01

    Oligodendrocyte lineage cells are susceptible to a variety of insults including hypoxia, excitotoxicity, and reactive oxygen species. Demyelination is a well-recognized feature of several CNS disorders including multiple sclerosis, white matter strokes, progressive multifocal leukoencephalopathy, and disorders due to mitochondrial DNA mutations. Although mitochondria have been implicated in the demise of oligodendrocyte lineage cells, the consequences of mitochondrial respiratory chain defects have not been examined. We determine the in vitro impact of established inhibitors of mitochondrial respiratory chain complex IV or cytochrome c oxidase on oligodendrocyte progenitor cells (OPCs) and mature oligodendrocytes as well as on differentiation capacity of OPCs from P0 rat. Injury to mature oligodendrocytes following complex IV inhibition was significantly greater than to OPCs, judged by cell detachment and mitochondrial membrane potential (MMP) changes, although viability of cells that remained attached was not compromised. Active mitochondria were abundant in processes of differentiated oligodendrocytes and MMP was significantly greater in differentiated oligodendrocytes than OPCs. MMP dissipated following complex IV inhibition in oligodendrocytes. Furthermore, complex IV inhibition impaired process formation within oligodendrocyte lineage cells. Injury to and impaired process formation of oligodendrocytes following complex IV inhibition has potentially important implications for the pathogenesis and repair of CNS myelin disorders. © 2010 Wiley-Liss, Inc. PMID:20665559

  7. Reorganization of Lipid Diffusion by Myelin Basic Protein as Revealed by STED Nanoscopy.

    PubMed

    Steshenko, Olena; Andrade, Débora M; Honigmann, Alf; Mueller, Veronika; Schneider, Falk; Sezgin, Erdinc; Hell, Stefan W; Simons, Mikael; Eggeling, Christian

    2016-06-01

    Myelin is a multilayered membrane that ensheathes axonal fibers in the vertebrate nervous system, allowing fast propagation of nerve action potentials. It contains densely packed lipids, lacks an actin-based cytocortex, and requires myelin basic protein (MBP) as its major structural component. This protein is the basic constituent of the proteinaceous meshwork that is localized between adjacent cytoplasmic membranes of the myelin sheath. Yet, it is not clear how MBP influences the organization and dynamics of the lipid constituents of myelin. Here, we used optical stimulated emission depletion super-resolution microscopy in combination with fluorescence correlation spectroscopy to assess the characteristics of diffusion of different fluorescent lipid analogs in myelin membrane sheets of cultured oligodendrocytes and in micrometer-sized domains that were induced by MBP in live epithelial PtK2 cells. Lipid diffusion was significantly faster and less anomalous both in oligodendrocytes and inside the MBP-rich domains of PtK2 cells compared with undisturbed live PtK2 cells. Our data show that MBP reorganizes lipid diffusion, possibly by preventing the buildup of an actin-based cytocortex and by preventing most membrane proteins from entering the myelin sheath region. Yet, in contrast to myelin sheets in oligodendrocytes, the MBP-induced domains in epithelial PtK2 cells demonstrate no change in lipid order, indicating that segregation of long-chain lipids into myelin sheets is a process specific to oligodendrocytes. PMID:27276262

  8. Astrocyte Activation via Stat3 Signaling Determines the Balance of Oligodendrocyte versus Schwann Cell Remyelination.

    PubMed

    Monteiro de Castro, Glaucia; Deja, Natalia A; Ma, Dan; Zhao, Chao; Franklin, Robin J M

    2015-09-01

    Remyelination within the central nervous system (CNS) most often is the result of oligodendrocyte progenitor cells differentiating into myelin-forming oligodendrocytes. In some cases, however, Schwann cells, the peripheral nervous system myelinating glia, are found remyelinating demyelinated regions of the CNS. The reason for this peripheral type of remyelination in the CNS and what governs it is unknown. Here, we used a conditional astrocytic phosphorylated signal transducer and activator of transcription 3 knockout mouse model to investigate the effect of abrogating astrocyte activation on remyelination after lysolecithin-induced demyelination of spinal cord white matter. We show that oligodendrocyte-mediated remyelination decreases and Schwann cell remyelination increases in lesioned knockout mice in comparison with lesioned controls. Our study shows that astrocyte activation plays a crucial role in the balance between Schwann cell and oligodendrocyte remyelination in the CNS, and provides further insight into remyelination of CNS axons by Schwann cells. PMID:26193667

  9. Astrocyte Activation via Stat3 Signaling Determines the Balance of Oligodendrocyte versus Schwann Cell Remyelination

    PubMed Central

    Monteiro de Castro, Glaucia; Deja, Natalia A.; Ma, Dan; Zhao, Chao; Franklin, Robin J.M.

    2016-01-01

    Remyelination within the central nervous system (CNS) most often is the result of oligodendrocyte progenitor cells differentiating into myelin-forming oligodendrocytes. In some cases, however, Schwann cells, the peripheral nervous system myelinating glia, are found remyelinating demyelinated regions of the CNS. The reason for this peripheral type of remyelination in the CNS and what governs it is unknown. Here, we used a conditional astrocytic phosphorylated signal transducer and activator of transcription 3 knockout mouse model to investigate the effect of abrogating astrocyte activation on remyelination after lysolecithin-induced demyelination of spinal cord white matter. We show that oligodendrocyte-mediated remyelination decreases and Schwann cell remyelination increases in lesioned knockout mice in comparison with lesioned controls. Our study shows that astrocyte activation plays a crucial role in the balance between Schwann cell and oligodendrocyte remyelination in the CNS, and provides further insight into remyelination of CNS axons by Schwann cells. PMID:26193667

  10. Anti-muscarinic adjunct therapy accelerates functional human oligodendrocyte repair.

    PubMed

    Abiraman, Kavitha; Pol, Suyog U; O'Bara, Melanie A; Chen, Guang-Di; Khaku, Zainab M; Wang, Jing; Thorn, David; Vedia, Bansi H; Ekwegbalu, Ezinne C; Li, Jun-Xu; Salvi, Richard J; Sim, Fraser J

    2015-02-25

    Therapeutic repair of myelin disorders may be limited by the relatively slow rate of human oligodendrocyte differentiation. To identify appropriate pharmacological targets with which to accelerate differentiation of human oligodendrocyte progenitors (hOPCs) directly, we used CD140a/O4-based FACS of human forebrain and microarray to hOPC-specific receptors. Among these, we identified CHRM3, a M3R muscarinic acetylcholine receptor, as being restricted to oligodendrocyte-biased CD140a(+)O4(+) cells. Muscarinic agonist treatment of hOPCs resulted in a specific and dose-dependent blockade of oligodendrocyte commitment. Conversely, when hOPCs were cocultured with human neurons, M3R antagonist treatment stimulated oligodendrocytic differentiation. Systemic treatment with solifenacin, an FDA-approved muscarinic receptor antagonist, increased oligodendrocyte differentiation of transplanted hOPCs in hypomyelinated shiverer/rag2 brain. Importantly, solifenacin treatment of engrafted animals reduced auditory brainstem response interpeak latency, indicative of increased conduction velocity and thereby enhanced functional repair. Therefore, solifenacin and other selective muscarinic antagonists represent new adjunct approaches to accelerate repair by engrafted human progenitors. PMID:25716865

  11. Evolution of myelin ultrastructure and the major structural myelin proteins.

    PubMed

    Inouye, Hideyo; Kirschner, Daniel A

    2016-06-15

    Myelin sheaths, as the specialized tissue wrapping the nerve fibers in the central and peripheral nervous systems (CNS and PNS), are responsible for rapid conduction of electrical signals in these fibers. We compare the nerve myelin sheaths of different phylogenetic origins-including mammal, rodent, bird, reptile, amphibian, lungfish, teleost, and elasmobranch-with respect to periodicities and inter-membrane separations at their cytoplasmic and extracellular appositions, and correlate these structural parameters with biochemical composition. P0 glycoprotein and P0-like proteins are present in PNS of terrestrial species or land vertebrates (Tetrapod) and in CNS and PNS of aquatic species. Proteolipid protein (PLP) is a major component only in the CNS myelin of terrestrial species and is involved in compaction of the extracellular apposition. The myelin structures of aquatic garfish and lungfish, which contain P0-like protein both in CNS and PNS, are similar to those of terrestrial species, indicating that they may be transitional organisms between water and land species. This article is part of a Special Issue entitled SI: Myelin Evolution. PMID:26519753

  12. Evolution of the CNS myelin gene regulatory program.

    PubMed

    Li, Huiliang; Richardson, William D

    2016-06-15

    Myelin is a specialized subcellular structure that evolved uniquely in vertebrates. A myelinated axon conducts action potentials many times faster than an unmyelinated axon of the same diameter; for the same conduction speed, the unmyelinated axon would need a much larger diameter and volume than its myelinated counterpart. Hence myelin speeds information transfer and saves space, allowing the evolution of a powerful yet portable brain. Myelination in the central nervous system (CNS) is controlled by a gene regulatory program that features a number of master transcriptional regulators including Olig1, Olig2 and Myrf. Olig family genes evolved from a single ancestral gene in non-chordates. Olig2, which executes multiple functions with regard to oligodendrocyte identity and development in vertebrates, might have evolved functional versatility through post-translational modification, especially phosphorylation, as illustrated by its evolutionarily conserved serine/threonine phospho-acceptor sites and its accumulation of serine residues during more recent stages of vertebrate evolution. Olig1, derived from a duplicated copy of Olig2 in early bony fish, is involved in oligodendrocyte development and is critical to remyelination in bony vertebrates, but is lost in birds. The origin of Myrf orthologs might be the result of DNA integration between an invading phage or bacterium and an early protist, producing a fusion protein capable of self-cleavage and DNA binding. Myrf seems to have adopted new functions in early vertebrates - initiation of the CNS myelination program as well as the maintenance of mature oligodendrocyte identity and myelin structure - by developing new ways to interact with DNA motifs specific to myelin genes. This article is part of a Special Issue entitled SI: Myelin Evolution. PMID:26474911

  13. Role of ERK1/2 MAPK Signaling in the Maintenance of Myelin and Axonal Integrity in the Adult CNS

    PubMed Central

    Ishii, Akihiro; Furusho, Miki; Dupree, Jeffrey L.

    2014-01-01

    Oligodendrocytes form myelin during postnatal development and then maintain a functional myelin sheath throughout adult life. While many regulators of developmental myelination have been identified, the signal transduction mechanisms that regulate oligodendrocyte functions in adulthood are not well understood. The extracellular signal-regulated kinases-1 and -2 (ERK1/2), downstream mediators of mitogen-activated protein kinases (MAPKs), have emerged as prominent regulators of myelin formation. Here, we investigated whether these signaling molecules are also required for myelin maintenance in the adult CNS. Inducible conditional ablation of Erk1/2 in oligodendrocytes of the adult CNS resulted in a downregulation of myelin gene expression. Although myelin thickness was reduced and some axons were demyelinated, the majority of axons were wrapped by intact myelin sheaths that appeared structurally normal. However, late onset of progressive axonal degeneration, accompanied by astrogliosis, microglial activation, partial loss of oligodendrocytes, and functional impairment, occurred in the adult mice lacking ERK1/2 activity. Conditional ablation of Fibroblast Growth Factor receptors-1 and -2 (FGFR1/2) in oligodendrocytes also resulted in downregulation of myelin gene expression and development of axonal degeneration as the mice aged. Further, the level of the key transcription factor myelin gene regulatory factor (Myrf) was downregulated or upregulated in mice with genetic loss or gain of ERK1/2 function, respectively. Together, our studies demonstrate that ERK1/2-MAPK signaling is required for the long-term maintenance of myelin and axonal integrity in the adult CNS and suggest that FGFR1/2 and Myrf may, in part, contribute to signaling upstream and downstream of ERK1/2 in maintaining these oligodendrocyte functions during adulthood. PMID:25429144

  14. Role of ERK1/2 MAPK signaling in the maintenance of myelin and axonal integrity in the adult CNS.

    PubMed

    Ishii, Akihiro; Furusho, Miki; Dupree, Jeffrey L; Bansal, Rashmi

    2014-11-26

    Oligodendrocytes form myelin during postnatal development and then maintain a functional myelin sheath throughout adult life. While many regulators of developmental myelination have been identified, the signal transduction mechanisms that regulate oligodendrocyte functions in adulthood are not well understood. The extracellular signal-regulated kinases-1 and -2 (ERK1/2), downstream mediators of mitogen-activated protein kinases (MAPKs), have emerged as prominent regulators of myelin formation. Here, we investigated whether these signaling molecules are also required for myelin maintenance in the adult CNS. Inducible conditional ablation of Erk1/2 in oligodendrocytes of the adult CNS resulted in a downregulation of myelin gene expression. Although myelin thickness was reduced and some axons were demyelinated, the majority of axons were wrapped by intact myelin sheaths that appeared structurally normal. However, late onset of progressive axonal degeneration, accompanied by astrogliosis, microglial activation, partial loss of oligodendrocytes, and functional impairment, occurred in the adult mice lacking ERK1/2 activity. Conditional ablation of Fibroblast Growth Factor receptors-1 and -2 (FGFR1/2) in oligodendrocytes also resulted in downregulation of myelin gene expression and development of axonal degeneration as the mice aged. Further, the level of the key transcription factor myelin gene regulatory factor (Myrf) was downregulated or upregulated in mice with genetic loss or gain of ERK1/2 function, respectively. Together, our studies demonstrate that ERK1/2-MAPK signaling is required for the long-term maintenance of myelin and axonal integrity in the adult CNS and suggest that FGFR1/2 and Myrf may, in part, contribute to signaling upstream and downstream of ERK1/2 in maintaining these oligodendrocyte functions during adulthood. PMID:25429144

  15. Epigenetic Modulation of Human Induced Pluripotent Stem Cell Differentiation to Oligodendrocytes

    PubMed Central

    Douvaras, Panagiotis; Rusielewicz, Tomasz; Kim, Kwi Hye; Haines, Jeffery D.; Casaccia, Patrizia; Fossati, Valentina

    2016-01-01

    Pluripotent stem cells provide an invaluable tool for generating human, disease-relevant cells. Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system, characterized by myelin damage. Oligodendrocytes are the myelinating cells of the central nervous system (CNS); they differentiate from progenitor cells, and their membranes ensheath axons, providing trophic support and allowing fast conduction velocity. The current understanding of oligodendrocyte biology was founded by rodent studies, where the establishment of repressive epigenetic marks on histone proteins, followed by activation of myelin genes, leads to lineage progression. To assess whether this epigenetic regulation is conserved across species, we differentiated human embryonic and induced pluripotent stem cells to oligodendrocytes and asked whether similar histone marks and relative enzymatic activities could be detected. The transcriptional levels of enzymes responsible for methylation and acetylation of histone marks were analyzed during oligodendrocyte differentiation, and the post-translational modifications on histones were detected using immunofluorescence. These studies showed that also in human cells, differentiation along the oligodendrocyte lineage is characterized by the acquisition of multiple repressive histone marks, including deacetylation of lysine residues on histone H3 and trimethylation of residues K9 and K27. These data suggest that the epigenetic modulation of oligodendrocyte identity is highly conserved across species. PMID:27110779

  16. Disturbed macro-connectivity in schizophrenia linked to oligodendrocyte dysfunction: from structural findings to molecules

    PubMed Central

    Cassoli, Juliana Silva; Guest, Paul C; Malchow, Berend; Schmitt, Andrea; Falkai, Peter; Martins-de-Souza, Daniel

    2015-01-01

    Schizophrenia is a severe psychiatric disorder with multi-factorial characteristics. A number of findings have shown disrupted synaptic connectivity in schizophrenia patients and emerging evidence suggests that this results from dysfunctional oligodendrocytes, the cells responsible for myelinating axons in white matter to promote neuronal conduction. The exact cause of this is not known, although recent imaging and molecular profiling studies of schizophrenia patients have identified changes in white matter tracts connecting multiple brain regions with effects on protein signaling networks involved in the myelination process. Further understanding of oligodendrocyte dysfunction in schizophrenia could lead to identification of novel drug targets for this devastating disease. PMID:27336040

  17. The receptor subunits generating NMDA receptor mediated currents in oligodendrocytes

    PubMed Central

    Burzomato, Valeria; Frugier, Guillaume; Pérez-Otaño, Isabel; Kittler, Josef T; Attwell, David

    2010-01-01

    NMDA receptors have been shown to contribute to glutamate-evoked currents in oligodendrocytes. Activation of these receptors damages myelin in ischaemia, in part because they are more weakly blocked by Mg2+ than are most neuronal NMDA receptors. This weak Mg2+ block was suggested to reflect an unusual subunit composition including the NR2C and NR3A subunits. Here we expressed NR1/NR2C and triplet NR1/NR2C/NR3A recombinant receptors in HEK cells and compared their currents with those of NMDA-evoked currents in rat cerebellar oligodendrocytes. NR1/NR2C/3A receptors were less blocked by 2 mm Mg2+ than were NR1/NR2C receptors (the remaining current was 30% and 18%, respectively, of that seen without added Mg2+) and showed less channel noise, suggesting a smaller single channel conductance. NMDA-evoked currents in oligodendrocytes showed a Mg2+ block (to 32%) similar to that observed for NR1/NR2C/NR3A and significantly different from that for NR1/NR2C receptors. Co-immunoprecipitation revealed interactions between NR1, NR2C and NR3A subunits in a purified myelin preparation from rat brain. These data are consistent with NMDA-evoked currents in oligodendrocytes reflecting the activation of receptors containing NR1, NR2C and NR3A subunits. PMID:20660562

  18. Making myelin basic protein -from mRNA transport to localized translation.

    PubMed

    Müller, Christina; Bauer, Nina M; Schäfer, Isabelle; White, Robin

    2013-01-01

    In the central nervous system (CNS) of most vertebrates, oligodendrocytes enwrap neuronal axons with extensions of their plasma membrane to form the myelin sheath. Several proteins are characteristically found in myelin of which myelin basic protein (MBP) is the second most abundant one after proteolipid protein. The lack of functional MBP in rodents results in a severe hypomyelinated phenotype in the CNS demonstrating its importance for myelin synthesis. Mbp mRNA is transported from the nucleus to the plasma membrane and is translated locally at the axon-glial contact site. Axonal properties such as diameter or electrical activity influence the degree of myelination. As oligodendrocytes can myelinate many axonal segments with varying properties, localized MBP translation represents an important part of a rapid and axon-tailored synthesis machinery. MBP's ability to compact cellular membranes may be problematic for the integrity of intracellular membranous organelles and can also explain why MBP is transported in oligodendrocytes in the form of an mRNA rather than as a protein. Here we review the recent findings regarding intracellular transport and signaling mechanisms leading to localized translation of Mbp mRNA in oligodendrocytes. More detailed insights into the MBP synthesis pathway are important for a better understanding of the myelination process and may foster the development of remyelination therapies for demyelinating diseases. PMID:24098271

  19. The effect of N-acetyl-aspartyl-glutamate and N-acetyl-aspartate on white matter oligodendrocytes.

    PubMed

    Kolodziejczyk, Karolina; Hamilton, Nicola B; Wade, Anna; Káradóttir, Ragnhildur; Attwell, David

    2009-06-01

    Elevations of the levels of N-acetyl-aspartyl-glutamate (NAAG) and N-acetyl-aspartate (NAA) are associated with myelin loss in the leucodystrophies Canavan's disease and Pelizaeus-Merzbacher-like disease. NAAG and NAA can activate and antagonize neuronal N-methyl-D-aspartate (NMDA) receptors, and also act on group II metabotropic glutamate receptors. Oligodendrocytes and their precursors have recently been shown to express NMDA receptors, and activation of these receptors in ischaemia leads to the death of oligodendrocyte precursors and the loss of myelin. This raises the possibility that the failure to develop myelin, or demyelination, occurring in the leucodystrophies could reflect an action of NAAG or NAA on oligodendrocyte NMDA receptors. However, since the putative subunit composition of NMDA receptors on oligodendrocytes differs from that of neuronal NMDA receptors, the effects of NAAG and NAA on them are unknown. We show that NAAG, but not NAA, evokes an inward membrane current in cerebellar white matter oligodendrocytes, which is reduced by NMDA receptor block (but not by block of metabotropic glutamate receptors). The size of the current evoked by NAAG, relative to that evoked by NMDA, was much smaller in oligodendrocytes than in neurons, and NAAG induced a rise in [Ca(2+)](i) in neurons but not in oligodendrocytes. These differences in the effect of NAAG on oligodendrocytes and neurons may reflect the aforementioned difference in receptor subunit composition. In addition, as a major part of the response in oligodendrocytes was blocked by tetrodotoxin (TTX), much of the NAAG-evoked current in oligodendrocytes is a secondary consequence of activating neuronal NMDA receptors. Six hours exposure to 1 mM NAAG did not lead to the death of cells in the white matter. We conclude that an action of NAAG on oligodendrocyte NMDA receptors is unlikely to be a major contributor to white matter damage in the leucodystrophies. PMID:19383832

  20. MicroRNA and Transcriptional Crosstalk in Myelinating Glia

    PubMed Central

    Svaren, John

    2014-01-01

    Several recent studies have addressed the important role of microRNA in regulation of differentiation of myelinating glia. While Schwann cells and oligodendrocytes in the peripheral and central nervous systems, respectively, exhibit significant morphological and regulatory differences, some aspects of transcriptional and microRNA regulation are shared between these two cell types. This review focuses on the intersection of microRNAs with transcriptional regulation in Schwann cell and oligodendrocyte differentiation. In particular, several microRNAs have been shown to modulate expression of critical transcription factors, and in turn, the regulation of microRNA expression is enmeshed within transcriptional networks that coordinate both coding gene and noncoding RNA profiles of myelinating cells. These hubs of regulation control both myelin gene expression as well as the cell cycle transitions of Schwann cells and oligodendrocytes as they terminally differentiate. In addition, some studies have begin to highlight the combinatorial effects of different microRNAs that establish the narrow range of gene regulation required for efficient and stable myelin formation. Overall, the integration of microRNA and transcriptional aspects will help elucidate mechanistic control of the myelination process. PMID:24979526

  1. The Major Myelin-Resident Protein PLP Is Transported to Myelin Membranes via a Transcytotic Mechanism: Involvement of Sulfatide

    PubMed Central

    Ozgen, Hande; Klunder, Bert; de Jonge, Jenny C.; Nomden, Anita; Plat, Annechien; Trifilieff, Elisabeth; de Vries, Hans; Hoekstra, Dick

    2014-01-01

    Myelin membranes are sheet-like extensions of oligodendrocytes that can be considered membrane domains distinct from the cell's plasma membrane. Consistent with the polarized nature of oligodendrocytes, we demonstrate that transcytotic transport of the major myelin-resident protein proteolipid protein (PLP) is a key element in the mechanism of myelin assembly. Upon biosynthesis, PLP traffics to myelin membranes via syntaxin 3-mediated docking at the apical-surface-like cell body plasma membrane, which is followed by subsequent internalization and transport to the basolateral-surface-like myelin sheet. Pulse-chase experiments, in conjunction with surface biotinylation and organelle fractionation, reveal that following biosynthesis, PLP is transported to the cell body surface in Triton X-100 (TX-100)-resistant microdomains. At the plasma membrane, PLP transiently resides within these microdomains and its lateral dissipation is followed by segregation into 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS)-resistant domains, internalization, and subsequent transport toward the myelin membrane. Sulfatide triggers PLP's reallocation from TX-100- into CHAPS-resistant membrane domains, while inhibition of sulfatide biosynthesis inhibits transcytotic PLP transport. Taking these findings together, we propose a model in which PLP transport to the myelin membrane proceeds via a transcytotic mechanism mediated by sulfatide and characterized by a conformational alteration and dynamic, i.e., transient, partitioning of PLP into distinct membrane microdomains involved in biosynthetic and transcytotic transport. PMID:25368380

  2. Remodeling myelination: implications for mechanisms of neural plasticity

    PubMed Central

    Chang, Kae-Jiun; Redmond, Stephanie A; Chan, Jonah R

    2016-01-01

    One of the most significant paradigm shifts in membrane remodeling is the emerging view that membrane transformation is not exclusively controlled by cytoskeletal rearrangement, but also by biophysical constraints, adhesive forces, membrane curvature and compaction. One of the most exquisite examples of membrane remodeling is myelination. The advent of myelin was instrumental in advancing the nervous system during vertebrate evolution. With more rapid and efficient communication between neurons, faster and more complex computations could be performed in a given time and space. Our knowledge of how myelin-forming oligodendrocytes select and wrap axons has been limited by insufficient spatial and temporal resolution. By virtue of recent technological advances, progress has clarified longstanding controversies in the field. Here we review insights into myelination, from target selection to axon wrapping and membrane compaction, and discuss how understanding these processes has unexpectedly opened new avenues of insight into myelination-centered mechanisms of neural plasticity. PMID:26814588

  3. Pre-Existing Mature Oligodendrocytes Do Not Contribute to Remyelination following Toxin-Induced Spinal Cord Demyelination

    PubMed Central

    Crawford, Abbe H.; Tripathi, Richa B.; Foerster, Sarah; McKenzie, Ian; Kougioumtzidou, Eleni; Grist, Matthew; Richardson, William D.; Franklin, Robin J.M.

    2016-01-01

    Remyelination is the regenerative response to demyelination. Although the oligodendrocyte progenitor is established as the major source of remyelinating cells, there is no conclusive evidence on whether mature, differentiated oligodendrocytes can also contribute to remyelination. Using two different inducible myelin-CreER mouse strains in which mature oligodendrocytes were prelabeled by the expression of membrane-bound Green fluorescent protein, we found that after focal spinal cord demyelination, the surrounding surviving labeled oligodendrocytes did not proliferate but remained at a consistent density. Furthermore, existing (prelabeled) oligodendrocytes showed no evidence of incorporation or migration into the lesioned area, or of process extension from the peripheral margins into the lesion. Thus, mature oligodendrocytes do not normally contribute to remyelination and are therefore not a promising target for regenerative therapy. PMID:26773350

  4. NMDA receptors mediate calcium accumulation in myelin during chemical ischaemia.

    PubMed

    Micu, I; Jiang, Q; Coderre, E; Ridsdale, A; Zhang, L; Woulfe, J; Yin, X; Trapp, B D; McRory, J E; Rehak, R; Zamponi, G W; Wang, W; Stys, P K

    2006-02-23

    Central nervous system myelin is a specialized structure produced by oligodendrocytes that ensheaths axons, allowing rapid and efficient saltatory conduction of action potentials. Many disorders promote damage to and eventual loss of the myelin sheath, which often results in significant neurological morbidity. However, little is known about the fundamental mechanisms that initiate myelin damage, with the assumption being that its fate follows that of the parent oligodendrocyte. Here we show that NMDA (N-methyl-d-aspartate) glutamate receptors mediate Ca2+ accumulation in central myelin in response to chemical ischaemia in vitro. Using two-photon microscopy, we imaged fluorescence of the Ca2+ indicator X-rhod-1 loaded into oligodendrocytes and the cytoplasmic compartment of the myelin sheath in adult rat optic nerves. The AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid)/kainate receptor antagonist NBQX completely blocked the ischaemic Ca2+ increase in oligodendroglial cell bodies, but only modestly reduced the Ca2+ increase in myelin. In contrast, the Ca2+ increase in myelin was abolished by broad-spectrum NMDA receptor antagonists (MK-801, 7-chlorokynurenic acid, d-AP5), but not by more selective blockers of NR2A and NR2B subunit-containing receptors (NVP-AAM077 and ifenprodil). In vitro ischaemia causes ultrastructural damage to both axon cylinders and myelin. NMDA receptor antagonism greatly reduced the damage to myelin. NR1, NR2 and NR3 subunits were detected in myelin by immunohistochemistry and immunoprecipitation, indicating that all necessary subunits are present for the formation of functional NMDA receptors. Our data show that the mature myelin sheath can respond independently to injurious stimuli. Given that axons are known to release glutamate, our finding that the Ca2+ increase was mediated in large part by activation of myelinic NMDA receptors suggests a new mechanism of axo-myelinic signalling. Such a mechanism may represent a

  5. The adhesion G protein-coupled receptor GPR56 is a cell-autonomous regulator of oligodendrocyte development

    PubMed Central

    Giera, Stefanie; Deng, Yiyu; Luo, Rong; Ackerman, Sarah D.; Mogha, Amit; Monk, Kelly R.; Ying, Yanqin; Jeong, Sung-Jin; Makinodan, Manabu; Bialas, Allison R.; Chang, Bernard S.; Stevens, Beth; Corfas, Gabriel; Piao, Xianhua

    2015-01-01

    Mutations in GPR56, a member of the adhesion G protein-coupled receptor family, cause a human brain malformation called bilateral frontoparietal polymicrogyria (BFPP). Magnetic resonance imaging (MRI) of BFPP brains reveals myelination defects in addition to brain malformation. However, the cellular role of GPR56 in oligodendrocyte development remains unknown. Here, we demonstrate that loss of Gpr56 leads to hypomyelination of the central nervous system in mice. GPR56 levels are abundant throughout early stages of oligodendrocyte development, but are downregulated in myelinating oligodendrocytes. Gpr56-knockout mice manifest with decreased oligodendrocyte precursor cell (OPC) proliferation and diminished levels of active RhoA, leading to fewer mature oligodendrocytes and a reduced number of myelinated axons in the corpus callosum and optic nerves. Conditional ablation of Gpr56 in OPCs leads to a reduced number of mature oligodendrocytes as seen in constitutive knockout of Gpr56. Together, our data define GPR56 as a cell-autonomous regulator of oligodendrocyte development. PMID:25607655

  6. Oligodendroglial membrane dynamics in relation to myelin biogenesis.

    PubMed

    Ozgen, Hande; Baron, Wia; Hoekstra, Dick; Kahya, Nicoletta

    2016-09-01

    In the central nervous system, oligodendrocytes synthesize a specialized membrane, the myelin membrane, which enwraps the axons in a multilamellar fashion to provide fast action potential conduction and to ensure axonal integrity. When compared to other membranes, the composition of myelin membranes is unique with its relatively high lipid to protein ratio. Their biogenesis is quite complex and requires a tight regulation of sequential events, which are deregulated in demyelinating diseases such as multiple sclerosis. To devise strategies for remedying such defects, it is crucial to understand molecular mechanisms that underlie myelin assembly and dynamics, including the ability of specific lipids to organize proteins and/or mediate protein-protein interactions in healthy versus diseased myelin membranes. The tight regulation of myelin membrane formation has been widely investigated with classical biochemical and cell biological techniques, both in vitro and in vivo. However, our knowledge about myelin membrane dynamics, such as membrane fluidity in conjunction with the movement/diffusion of proteins and lipids in the membrane and the specificity and role of distinct lipid-protein and protein-protein interactions, is limited. Here, we provide an overview of recent findings about the myelin structure in terms of myelin lipids, proteins and membrane microdomains. To give insight into myelin membrane dynamics, we will particularly highlight the application of model membranes and advanced biophysical techniques, i.e., approaches which clearly provide an added value to insight obtained by classical biochemical techniques. PMID:27141942

  7. Remyelination reporter reveals prolonged refinement of spontaneously regenerated myelin

    PubMed Central

    Powers, Berit E.; Sellers, Drew L.; Lovelett, Emilie A.; Cheung, Willy; Aalami, Sheida P.; Zapertov, Nikolai; Maris, Don O.; Horner, Philip J.

    2013-01-01

    Neurological diseases and trauma often cause demyelination, resulting in the disruption of axonal function and integrity. Endogenous remyelination promotes recovery, but the process is not well understood because no method exists to definitively distinguish regenerated from preexisting myelin. To date, remyelinated segments have been defined as anything abnormally short and thin, without empirical data to corroborate these morphological assumptions. To definitively identify regenerated myelin, we used a transgenic mouse with an inducible membrane-bound reporter and targeted Cre recombinase expression to a subset of glial progenitor cells after spinal cord injury, yielding remarkably clear visualization of spontaneously regenerated myelin in vivo. Early after injury, the mean length of sheaths regenerated by Schwann cells and oligodendrocytes (OLs) was significantly shorter than control, uninjured myelin, confirming past assumptions. However, OL-regenerated sheaths elongated progressively over 6 mo to approach control values. Moreover, OL-regenerated myelin thickness was not significantly different from control myelin at most time points after injury. Thus, many newly formed OL sheaths were neither thinner nor shorter than control myelin, vitiating accepted dogmas of what constitutes regenerated myelin. We conclude that remyelination, once thought to be static, is dynamic and elongates independently of axonal growth, in contrast to stretch-based mechanisms proposed in development. Further, without clear identification, past assessments have underestimated the extent and quality of regenerated myelin. PMID:23431182

  8. Astrocytes phagocytose focal dystrophies from shortening myelin segments in the optic nerve of Xenopus laevis at metamorphosis

    PubMed Central

    Mills, Elizabeth A.; Davis, Chung-ha O.; Bushong, Eric A.; Boassa, Daniela; Kim, Keun-Young; Ellisman, Mark H.; Marsh-Armstrong, Nicholas

    2015-01-01

    Oligodendrocytes can adapt to increases in axon diameter through the addition of membrane wraps to myelin segments. Here, we report that myelin segments can also decrease their length in response to optic nerve (ON) shortening during Xenopus laevis metamorphic remodeling. EM-based analyses revealed that myelin segment shortening is accomplished by focal myelin-axon detachments and protrusions from otherwise intact myelin segments. Astrocyte processes remove these focal myelin dystrophies using known phagocytic machinery, including the opsonin milk fat globule-EGF factor 8 (Mfge8) and the downstream effector ras-related C3 botulinum toxin substrate 1 (Rac1). By the end of metamorphic nerve shortening, one-quarter of all myelin in the ON is enwrapped or internalized by astrocytes. As opposed to the removal of degenerating myelin by macrophages, which is usually associated with axonal pathologies, astrocytes selectively remove large amounts of myelin without damaging axons during this developmental remodeling event. PMID:26240339

  9. Astrocytes phagocytose focal dystrophies from shortening myelin segments in the optic nerve of Xenopus laevis at metamorphosis.

    PubMed

    Mills, Elizabeth A; Davis, Chung-ha O; Bushong, Eric A; Boassa, Daniela; Kim, Keun-Young; Ellisman, Mark H; Marsh-Armstrong, Nicholas

    2015-08-18

    Oligodendrocytes can adapt to increases in axon diameter through the addition of membrane wraps to myelin segments. Here, we report that myelin segments can also decrease their length in response to optic nerve (ON) shortening during Xenopus laevis metamorphic remodeling. EM-based analyses revealed that myelin segment shortening is accomplished by focal myelin-axon detachments and protrusions from otherwise intact myelin segments. Astrocyte processes remove these focal myelin dystrophies using known phagocytic machinery, including the opsonin milk fat globule-EGF factor 8 (Mfge8) and the downstream effector ras-related C3 botulinum toxin substrate 1 (Rac1). By the end of metamorphic nerve shortening, one-quarter of all myelin in the ON is enwrapped or internalized by astrocytes. As opposed to the removal of degenerating myelin by macrophages, which is usually associated with axonal pathologies, astrocytes selectively remove large amounts of myelin without damaging axons during this developmental remodeling event. PMID:26240339

  10. ER Chaperone BiP/GRP78 Is Required for Myelinating Cell Survival and Provides Protection during Experimental Autoimmune Encephalomyelitis

    PubMed Central

    Hussien, Yassir; Podojil, Joseph R.; Robinson, Andrew P.; Lee, Amy S.; Miller, Steven D.

    2015-01-01

    Myelinating cells synthesize large amounts of membrane protein through the secretory pathway, which makes these cells particularly sensitive to perturbations of the endoplasmic reticulum (ER). Ig binding protein (BiP), also known as glucose-regulated protein 78 (GRP78), is a critical ER chaperone that also plays a pivotal role in controlling the cellular response to ER stress. To examine the potential importance of BiP to myelinating cells, we used a conditional knock-out approach to BiP gene inactivation in oligodendrocytes during development, in adulthood, and in response to experimental autoimmune encephalomyelitis (EAE), an animal model of the inflammatory demyelinating disorder multiple sclerosis (MS). During development, mice lacking functional BiP gene expression in oligodendrocytes developed tremors and ataxia and died before reaching maturity. When BiP gene inactivation in oligodendrocytes was initiated in adulthood, the mice displayed severe neurological symptoms including tremors and hind-limb paralysis. The inactivation of BiP in oligodendrocytes during development or in adulthood resulted in oligodendrocyte loss and corresponding severe myelin abnormalities. Mice heterozygous for the oligodendrocyte-specific inactivation of BiP, which were phenotypically normal without evidence of neuropathology, displayed an exacerbated response to EAE that correlated with an increased loss of oligodendrocytes. Furthermore, mice in which the BiP gene was specifically inactivated in developing Schwann cells displayed tremor that progressed to hindlimb paralysis, which correlated with diminished numbers of myelinating Schwann cells and severe PNS hypomyelination. These studies demonstrate that BiP is critical for myelinating cell survival and contributes to the protective response of oligodendrocyte against inflammatory demyelination. SIGNIFICANCE STATEMENT The myelinating cells, oligodendrocytes in the CNS and Schwann cells in the PNS, are responsible for synthesizing

  11. Liver X receptors alpha and beta promote myelination and remyelination in the cerebellum

    PubMed Central

    Meffre, Delphine; Shackleford, Ghjuvan’Ghjacumu; Hichor, Mehdi; Gorgievski, Victor; Tzavara, Eleni T.; Trousson, Amalia; Ghoumari, Abdel M.; Deboux, Cyrille; Nait Oumesmar, Brahim; Liere, Philippe; Schumacher, Michael; Baulieu, Etienne-Emile; Charbonnier, Frédéric; Grenier, Julien; Massaad, Charbel

    2015-01-01

    The identification of new pathways governing myelination provides innovative avenues for remyelination. Liver X receptors (LXRs) α and β are nuclear receptors activated by oxysterols that originated from the oxidation of cholesterol. They are crucial for cholesterol homeostasis, a major lipid constituent of myelin sheaths that are formed by oligodendrocytes. However, the role of LXRs in myelin generation and maintenance is poorly understood. Here, we show that LXRs are involved in myelination and remyelination processes. LXRs and their ligands are present in oligodendrocytes. We found that mice invalidated for LXRs exhibit altered motor coordination and spatial learning, thinner myelin sheaths, and reduced myelin gene expression. Conversely, activation of LXRs by either 25-hydroxycholesterol or synthetic TO901317 stimulates myelin gene expression at the promoter, mRNA, and protein levels, directly implicating LXRα/β in the transcriptional control of myelin gene expression. Interestingly, activation of LXRs also promotes oligodendroglial cell maturation and remyelination after lysolecithin-induced demyelination of organotypic cerebellar slice cultures. Together, our findings represent a conceptual advance in the transcriptional control of myelin gene expression and strongly support a new role of LXRs as positive modulators in central (re)myelination processes. PMID:26023184

  12. The role of myelin in Theiler's virus persistence in the central nervous system.

    PubMed

    Roussarie, Jean-Pierre; Ruffié, Claude; Brahic, Michel

    2007-02-01

    Theiler's virus, a picornavirus, persists for life in the central nervous system of mouse and causes a demyelinating disease that is a model for multiple sclerosis. The virus infects neurons first but persists in white matter glial cells, mainly oligodendrocytes and macrophages. The mechanism, by which the virus traffics from neurons to glial cells, and the respective roles of oligodendrocytes and macrophages in persistence are poorly understood. We took advantage of our previous finding that the shiverer mouse, a mutant with a deletion in the myelin basic protein gene (Mbp), is resistant to persistent infection to examine the role of myelin in persistence. Using immune chimeras, we show that resistance is not mediated by immune responses or by an efficient recruitment of inflammatory cells into the central nervous system. With both in vivo and in vitro experiments, we show that the mutation does not impair the permissiveness of neurons, oligodendrocytes, and macrophages to the virus. We demonstrate that viral antigens are present in cytoplasmic channels of myelin during persistent infection of wild-type mice. Using the optic nerve as a model, we show that the virus traffics from the axons of retinal ganglion cells to the cytoplasmic channels of myelin, and that this traffic is impaired by the shiverer mutation. These results uncover an unsuspected axon to myelin traffic of Theiler's virus and the essential role played by the infection of myelin/oligodendrocyte in persistence. PMID:17305428

  13. α-Synuclein impairs oligodendrocyte progenitor maturation in multiple system atrophy.

    PubMed

    May, Verena E L; Ettle, Benjamin; Poehler, Anne-Maria; Nuber, Silke; Ubhi, Kiren; Rockenstein, Edward; Winner, Beate; Wegner, Michael; Masliah, Eliezer; Winkler, Jürgen

    2014-10-01

    Multiple system atrophy (MSA), an atypical parkinsonian disorder, is characterized by α-synuclein (α-syn(+)) cytoplasmatic inclusions in mature oligodendrocytes. Oligodendrocyte progenitor cells (OPCs) represent a distinct cell population with the potential to replace dysfunctional oligodendrocytes. However, the role of OPCs in MSA and their potential to replace mature oligodendrocytes is still unclear. A postmortem analysis in MSA patients revealed α-syn within OPCs and an increased number of striatal OPCs. In an MSA mouse model, an age-dependent increase of dividing OPCs within the striatum and the cortex was detected. Despite of myelin loss, there was no reduction of mature oligodendrocytes in the corpus callosum or the striatum. Dissecting the underlying molecular mechanisms an oligodendroglial cell line expressing human α-syn revealed that α-syn delays OPC maturation by severely downregulating myelin-gene regulatory factor and myelin basic protein. Brain-derived neurotrophic factor was reduced in MSA models and its in vitro supplementation partially restored the phenotype. Taken together, efficacious induction of OPC maturation may open the window to restore glial and neuronal function in MSA. PMID:24698767

  14. Is cell migration or proliferation dominant in the formation of linear arrays of oligodendrocytes?

    PubMed

    Walsh, Darragh M; Röth, Philipp T; Holmes, William R; Landman, Kerry A; Merson, Tobias D; Hughes, Barry D

    2016-10-01

    Oligodendrocytes are the myelin-producing cells of the central nervous system that are responsible for electrically insulating axons to speed the propagation of electrical impulses. A striking feature of oligodendrocyte development within white matter is that the cell bodies of many oligodendrocyte progenitor cells become organised into discrete linear arrays of three or more cells before they differentiate into myelin-producing oligodendrocytes. These linear arrays align parallel to the direction of the axons within white matter tracts and are believed to play an important role in the co-ordination of myelination. Guided by experimental data on the abundance and composition of linear arrays in the corpus callosum of the postnatal mouse brain, we construct discrete and continuous models of linear array generation to specifically investigate the relative influence of cell migration, proliferation, differentiation and death of oligodendroglia upon the genesis of linear arrays during early postnatal development. We demonstrate that only models that incorporate significant cell migration can replicate all of the experimental observations on number of arrays, number of cells in arrays and total cell count of oligodendroglia within a given area of the corpus callosum. These models are also necessary to accurately reflect experimental data on the abundance of linear arrays composed of oligodendrocytes that derive from progenitors of different clonal origins. PMID:27343034

  15. Myelin Recovery in Multiple Sclerosis: The Challenge of Remyelination

    PubMed Central

    Podbielska, Maria; Banik, Naren L.; Kurowska, Ewa; Hogan, Edward L.

    2013-01-01

    Multiple sclerosis (MS) is the most common demyelinating and an autoimmune disease of the central nervous system characterized by immune-mediated myelin and axonal damage, and chronic axonal loss attributable to the absence of myelin sheaths. T cell subsets (Th1, Th2, Th17, CD8+, NKT, CD4+CD25+ T regulatory cells) and B cells are involved in this disorder, thus new MS therapies seek damage prevention by resetting multiple components of the immune system. The currently approved therapies are immunoregulatory and reduce the number and rate of lesion formation but are only partially effective. This review summarizes current understanding of the processes at issue: myelination, demyelination and remyelination—with emphasis upon myelin composition/architecture and oligodendrocyte maturation and differentiation. The translational options target oligodendrocyte protection and myelin repair in animal models and assess their relevance in human. Remyelination may be enhanced by signals that promote myelin formation and repair. The crucial question of why remyelination fails is approached is several ways by examining the role in remyelination of available MS medications and avenues being actively pursued to promote remyelination including: (i) cytokine-based immune-intervention (targeting calpain inhibition), (ii) antigen-based immunomodulation (targeting glycolipid-reactive iNKT cells and sphingoid mediated inflammation) and (iii) recombinant monoclonal antibodies-induced remyelination. PMID:24961530

  16. Rapid production of new oligodendrocytes is required in the earliest stages of motor-skill learning.

    PubMed

    Xiao, Lin; Ohayon, David; McKenzie, Ian A; Sinclair-Wilson, Alexander; Wright, Jordan L; Fudge, Alexander D; Emery, Ben; Li, Huiliang; Richardson, William D

    2016-09-01

    We identified mRNA encoding the ecto-enzyme Enpp6 as a marker of newly forming oligodendrocytes, and used Enpp6 in situ hybridization to track oligodendrocyte differentiation in adult mice as they learned a motor skill (running on a wheel with unevenly spaced rungs). Within just 2.5 h of exposure to the complex wheel, production of Enpp6-expressing immature oligodendrocytes was accelerated in subcortical white matter; within 4 h, it was accelerated in motor cortex. Conditional deletion of myelin regulatory factor (Myrf) in oligodendrocyte precursors blocked formation of new Enpp6(+) oligodendrocytes and impaired learning within the same ∼2-3 h time frame. This very early requirement for oligodendrocytes suggests a direct and active role in learning, closely linked to synaptic strengthening. Running performance of normal mice continued to improve over the following week accompanied by secondary waves of oligodendrocyte precursor proliferation and differentiation. We concluded that new oligodendrocytes contribute to both early and late stages of motor skill learning. PMID:27455109

  17. Insulin-like growth factor I/somatomedin C: a potent inducer of oligodendrocyte development

    SciTech Connect

    McMorris, F.A.; Smith, T.M.; DeSalvo, S.; Furlanetto, R.W.

    1986-02-01

    Cell cultures established from cerebrum of 1-day-old rats were used to investigate hormonal regulation of the development of oligodendrocytes, which synthesize myelin in the central nervous system. The number of oligodendrocytes that developed was preferentially increased by insulin, or by insulin-like growth factor I (IGF-I), also known as somatomedin C. High concentrations of insulin were required for substantial induction of oligodendrocyte development, whereas only 3.3 ng of IGF-I per ml was needed for a 2-fold increase in oligodendrocyte numbers. At an IGF-I concentration of 100 ng/ml, oligodendrocyte numbers were increased 6-fold in cultures grown in the presence of 10% fetal bovine serum, or up to 60-fold in cultures maintained in serum-free medium. IGF-I produced less than a 2-fold increase in the number of nonoligodendroglial cells in the same cultures. Type I IGF receptors were identified on oligodendrocytes and on a putative oligodendrocyte precursor cell population identified by using mouse monoclonal antibody A2B5. Radioligand binding assays were done. These results indicate that IGF-I is a potent inducer of oligodendrocyte development and suggest a possible mechanism based on IGF deficiency for the hypomyelination that results from early postnatal malnutrition.

  18. Origins of oligodendrocytes in the cerebellum, whose development is controlled by the transcription factor, Sox9.

    PubMed

    Hashimoto, Ryoya; Hori, Kei; Owa, Tomoo; Miyashita, Satoshi; Dewa, Kenichi; Masuyama, Norihisa; Sakai, Kazuhisa; Hayase, Yoneko; Seto, Yusuke; Inoue, Yukiko U; Inoue, Takayoshi; Ichinohe, Noritaka; Kawaguchi, Yoshiya; Akiyama, Haruhiko; Koizumi, Schuichi; Hoshino, Mikio

    2016-05-01

    Development of oligodendrocytes, myelin-forming glia in the central nervous system (CNS), proceeds on a protracted schedule. Specification of oligodendrocyte progenitor cells (OPCs) begins early in development, whereas their terminal differentiation occurs at late embryonic and postnatal periods. However, for oligodendrocytes in the cerebellum, the developmental origins and the molecular machinery to control these distinct steps remain unclear. By in vivo fate mapping and immunohistochemical analyses, we obtained evidence that the majority of oligodendrocytes in the cerebellum originate from the Olig2-expressing neuroepithelial domain in the ventral rhombomere 1 (r1), while about 6% of cerebellar oligodendrocytes are produced in the cerebellar ventricular zone. Furthermore, to elucidate the molecular determinants that regulate their development, we analyzed mice in which the transcription factor Sox9 was specifically ablated from the cerebellum, ventral r1 and caudal midbrain by means of the Cre/loxP recombination system. This resulted in a delay in the birth of OPCs and subsequent developmental aberrations in these cells in the Sox9-deficient mice. In addition, we observed altered proliferation of OPCs, resulting in a decrease in oligodendrocyte numbers that accompanied an attenuation of the differentiation and an increased rate of apoptosis. Results from in vitro assays using oligodendrocyte-enriched cultures further supported our observations from in vivo experiments. These data suggest that Sox9 participates in the development of oligodendrocytes in the cerebellum, by regulating the timing of their generation, proliferation, differentiation and survival. PMID:26940020

  19. Myelin from MAG-deficient mice is a strong inhibitor of neurite outgrowth.

    PubMed

    Ng, W P; Cartel, N; Li, C; Roder, J; Lozano, A

    1996-03-22

    Myelin-associated glycoprotein (MAG) has potent neurite outgrowth inhibitory activity in vitro. To assess the importance of MAG in the neurite outgrowth inhibitory activity in CNS myelin, we used an in vitro bioassay to characterize neurite growth on CNS myelin derived from mice carrying a null mutation of the MAG gene. Myelin proteins from MAG-deficient mice inhibited neurite outgrowth to a similar degree to the wild-type CNS myelin. These results suggest that CNS myelin molecules other than MAG exert strong inhibitory effects on the growth of neurites. PMID:8724661

  20. Characterization of the Shark Myelin Po Protein

    PubMed Central

    Rotenstein, L.; Herath, K.; Gould, R.M.; de Bellard, M.E.

    2008-01-01

    Myelin, the insulating sheath made by extensive plasma membrane wrappings is dependent on the presence of highly adhesive molecules that keep the two sides of the membrane in tight contact. The Po glycoprotein (Po) is the major component of the peripheral nervous system (PNS) myelin of mammals. The exact role that Po protein has played in the evolution of myelin is still unclear, but several phylogenetic observations point to it as a crucial component in the development of myelin as a multi-lamellar membrane structure. Sharks, which appeared in evolution about 400 million years ago, are the first fully myelinated organisms. In this study we set out to investigate the expression pattern of shark myelin Po as a way of understanding how it might have played a role in the evolution of myelin in the central nervous system. We found that shark have more than two isoforms (32, 28 and 25kD), and that some of these might not be fully functional because they lack the domains known for Po homophilic adhesion. PMID:18635929

  1. Identification of A2B5-positive putative oligodendrocyte progenitor cells and A2B5-positive astrocytes in adult human white matter.

    PubMed

    Scolding, N J; Rayner, P J; Compston, D A

    1999-03-01

    Spontaneous remyelination of previously demyelinated axons is found in a substantial minority of acute and chronic lesions in multiple sclerosis. In the rodent, central remyelination restores saltatory conduction and helps restore limb function, and it seems likely that endogenous myelin repair contributes to neurological recovery in multiple sclerosis. However, the identity of the remyelinating cell remains enigmatic. Fully differentiated oligodendrocytes have very limited capacity for recapitulating their developmental activities and re-engaging myelination pathways. Proliferative oligodendrocyte progenitors--often known as O-2A cells because of their ability to differentiate in vitro into either oligodendrocytes or ("type 2") astrocytes--are, in contrast, extremely efficient at myelin repair either spontaneously, or after transplantation into the de- or dysmyelinated CNS. Oligodendrocyte progenitors are present in both developing and adult rodent CNS. We have previously demonstrated that proliferative oligodendrocyte progenitors are present in cultures prepared from the adult human CNS. Here, using fresh tissue print preparations, we report that cells with processes and the A2B5-positive immunophenotype of proliferative oligodendrocyte progenitors are present in situ in adult human white matter. This technique also reveals the occurrence of A2B5-positive astrocytes, a cell also not previously identified in the normal adult human CNS. In the light of the rodent data showing the importance of oligodendrocyte progenitors in myelin repair, our findings suggesting the presence of progenitors in the adult human brain may have significant implications for spontaneous remyelination in multiple sclerosis and other demyelinating conditions. PMID:10051212

  2. Clostridium perfringens Epsilon Toxin Causes Selective Death of Mature Oligodendrocytes and Central Nervous System Demyelination

    PubMed Central

    Linden, Jennifer R.; Ma, Yinghua; Zhao, Baohua; Harris, Jason Michael; Rumah, Kareem Rashid; Schaeren-Wiemers, Nicole

    2015-01-01

    ABSTRACT Clostridium perfringens epsilon toxin (ε-toxin) is responsible for a devastating multifocal central nervous system (CNS) white matter disease in ruminant animals. The mechanism by which ε-toxin causes white matter damage is poorly understood. In this study, we sought to determine the molecular and cellular mechanisms by which ε-toxin causes pathological changes to white matter. In primary CNS cultures, ε-toxin binds to and kills oligodendrocytes but not astrocytes, microglia, or neurons. In cerebellar organotypic culture, ε-toxin induces demyelination, which occurs in a time- and dose-dependent manner, while preserving neurons, astrocytes, and microglia. ε-Toxin specificity for oligodendrocytes was confirmed using enriched glial culture. Sensitivity to ε-toxin is developmentally regulated, as only mature oligodendrocytes are susceptible to ε-toxin; oligodendrocyte progenitor cells are not. ε-Toxin sensitivity is also dependent on oligodendrocyte expression of the proteolipid myelin and lymphocyte protein (MAL), as MAL-deficient oligodendrocytes are insensitive to ε-toxin. In addition, ε-toxin binding to white matter follows the spatial and temporal pattern of MAL expression. A neutralizing antibody against ε-toxin inhibits oligodendrocyte death and demyelination. This study provides several novel insights into the action of ε-toxin in the CNS. (i) ε-Toxin causes selective oligodendrocyte death while preserving all other neural elements. (ii) ε-Toxin-mediated oligodendrocyte death is a cell autonomous effect. (iii) The effects of ε-toxin on the oligodendrocyte lineage are restricted to mature oligodendrocytes. (iv) Expression of the developmentally regulated proteolipid MAL is required for the cytotoxic effects. (v) The cytotoxic effects of ε-toxin can be abrogated by an ε-toxin neutralizing antibody. PMID:26081637

  3. Protein aggregate formation in oligodendrocytes: tau and the cytoskeleton at the intersection of neuroprotection and neurodegeneration.

    PubMed

    Richter-Landsberg, Christiane

    2016-03-01

    Oligodendrocytes are dependent on an intact, dynamic microtubule (MT) network, which participates in the elaboration and stabilization of myelin forming extensions, and is essential for cellular sorting processes. The microtubule-associated protein tau is constituent of oligodendrocytes. During culture maturation it is developmentally regulated and important for MT stability, MT formation and intracellular trafficking. Downregulation of tau impairs process outgrowth and the transport of myelin basic protein (MBP) mRNA to the cell periphery. Cells fail to differentiate into MBP-expressing, sheet-forming oligodendrocytes. Tau-positive inclusions originating in oligodendrocytes and white matter pathology are prominent in frontotemporal dementias, such as Pick's disease, progressive supranuclear palsy and corticobasal degeneration. An impairment or overload of the proteolytic degradation systems, i.e. the ubiquitin proteasomal system and the lysosomal degradation pathway, has been connected to the formation of protein aggregates. Large protein aggregates are excluded from the proteasome and degraded by autophagy, which is a highly selective process and requires receptor proteins for ubiquitinated proteins, including histone deacetylase 6 (HDAC6). HDAC6 is present in oligodendrocytes, and α-tubulin and tau are substrates of HDAC6. In this review our current knowledge of the role of tau and protein aggregate formation in oligodendrocyte cell culture systems is summarized. PMID:26083267

  4. Oligodendrocyte Precursor Cells Synthesize Neuromodulatory Factors

    PubMed Central

    Sakry, Dominik; Yigit, Hatice; Dimou, Leda; Trotter, Jacqueline

    2015-01-01

    NG2 protein-expressing oligodendrocyte progenitor cells (OPC) are a persisting and major glial cell population in the adult mammalian brain. Direct synaptic innervation of OPC by neurons throughout the brain together with their ability to sense neuronal network activity raises the question of additional physiological roles of OPC, supplementary to generating myelinating oligodendrocytes. In this study we investigated whether OPC express neuromodulatory factors, typically synthesized by other CNS cell types. Our results show that OPC express two well-characterized neuromodulatory proteins: Prostaglandin D2 synthase (PTGDS) and neuronal Pentraxin 2 (Nptx2/Narp). Expression levels of the enzyme PTGDS are influenced in cultured OPC by the NG2 intracellular region which can be released by cleavage and localizes to glial nuclei upon transfection. Furthermore PTGDS mRNA levels are reduced in OPC from NG2-KO mouse brain compared to WT cells after isolation by cell sorting and direct analysis. These results show that OPC can contribute to the expression of these proteins within the CNS and suggest PTGDS expression as a downstream target of NG2 signaling. PMID:25966014

  5. SNX27, a protein involved in down syndrome, regulates GPR17 trafficking and oligodendrocyte differentiation.

    PubMed

    Meraviglia, Veronica; Ulivi, Alessandro Francesco; Boccazzi, Marta; Valenza, Fabiola; Fratangeli, Alessandra; Passafaro, Maria; Lecca, Davide; Stagni, Fiorenza; Giacomini, Andrea; Bartesaghi, Renata; Abbracchio, Maria P; Ceruti, Stefania; Rosa, Patrizia

    2016-08-01

    The G protein-coupled receptor 17 (GPR17) plays crucial roles in myelination. It is highly expressed during transition of oligodendrocyte progenitor cells to immature oligodendrocytes, but, after this stage, it must be down-regulated to allow generation of mature myelinating cells. After endocytosis, GPR17 is sorted into lysosomes for degradation or recycled to the plasma membrane. Balance between degradation and recycling is important for modulation of receptor levels at the cell surface and thus for the silencing/activation of GPR17-signaling pathways that, in turn, affect oligodendrocyte differentiation. The molecular mechanisms at the basis of these processes are still partially unknown and their characterization will allow a better understanding of myelination and provide cues to interpret the consequences of GPR17 dysfunction in diseases. Here, we demonstrate that the endocytic trafficking of GPR17 is mediated by the interaction of a type I PDZ-binding motif located at the C-terminus of the receptor and SNX27, a recently identified protein of the endosome-associated retromer complex and whose functions in oligodendrocytes have never been studied. SNX27 knock-down significantly reduces GPR17 plasma membrane recycling in differentiating oligodendrocytes while accelerating cells' terminal maturation. Interestingly, trisomy-linked down-regulation of SNX27 expression in the brain of Ts65Dn mice, a model of Down syndrome, correlates with a decrease in GPR17(+) cells and an increase in mature oligodendrocytes, which, however, fail in reaching full maturation, eventually leading to hypomyelination. Our data demonstrate that SNX27 modulates GPR17 plasma membrane recycling and stability, and that disruption of the SNX27/GPR17 interaction might contribute to pathological oligodendrocyte differentiation defects. GLIA 2016. GLIA 2016;64:1437-1460. PMID:27270750

  6. Neuronal activity regulates remyelination via glutamate signalling to oligodendrocyte progenitors

    PubMed Central

    Gautier, Hélène O. B.; Evans, Kimberley A.; Volbracht, Katrin; James, Rachel; Sitnikov, Sergey; Lundgaard, Iben; James, Fiona; Lao-Peregrin, Cristina; Reynolds, Richard; Franklin, Robin J. M.; Káradóttir, Ragnhildur T

    2015-01-01

    Myelin regeneration can occur spontaneously in demyelinating diseases such as multiple sclerosis (MS). However, the underlying mechanisms and causes of its frequent failure remain incompletely understood. Here we show, using an in-vivo remyelination model, that demyelinated axons are electrically active and generate de novo synapses with recruited oligodendrocyte progenitor cells (OPCs), which, early after lesion induction, sense neuronal activity by expressing AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate receptors. Blocking neuronal activity, axonal vesicular release or AMPA receptors in demyelinated lesions results in reduced remyelination. In the absence of neuronal activity there is a ∼6-fold increase in OPC number within the lesions and a reduced proportion of differentiated oligodendrocytes. These findings reveal that neuronal activity and release of glutamate instruct OPCs to differentiate into new myelinating oligodendrocytes that recover lost function. Co-localization of OPCs with the presynaptic protein VGluT2 in MS lesions implies that this mechanism may provide novel targets to therapeutically enhance remyelination. PMID:26439639

  7. Neuronal activity regulates remyelination via glutamate signalling to oligodendrocyte progenitors.

    PubMed

    Gautier, Hélène O B; Evans, Kimberley A; Volbracht, Katrin; James, Rachel; Sitnikov, Sergey; Lundgaard, Iben; James, Fiona; Lao-Peregrin, Cristina; Reynolds, Richard; Franklin, Robin J M; Káradóttir, Ragnhildur T

    2015-01-01

    Myelin regeneration can occur spontaneously in demyelinating diseases such as multiple sclerosis (MS). However, the underlying mechanisms and causes of its frequent failure remain incompletely understood. Here we show, using an in-vivo remyelination model, that demyelinated axons are electrically active and generate de novo synapses with recruited oligodendrocyte progenitor cells (OPCs), which, early after lesion induction, sense neuronal activity by expressing AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate receptors. Blocking neuronal activity, axonal vesicular release or AMPA receptors in demyelinated lesions results in reduced remyelination. In the absence of neuronal activity there is a ∼6-fold increase in OPC number within the lesions and a reduced proportion of differentiated oligodendrocytes. These findings reveal that neuronal activity and release of glutamate instruct OPCs to differentiate into new myelinating oligodendrocytes that recover lost function. Co-localization of OPCs with the presynaptic protein VGluT2 in MS lesions implies that this mechanism may provide novel targets to therapeutically enhance remyelination. PMID:26439639

  8. Proteolipid Protein Is Required for Transport of Sirtuin 2 into CNS Myelin

    PubMed Central

    Werner, Hauke B.; Kuhlmann, Katja; Shen, Siming; Uecker, Marina; Schardt, Anke; Dimova, Kalina; Orfaniotou, Foteini; Dhaunchak, Ajit; Brinkmann, Bastian G.; Möbius, Wiebke; Guarente, Lenny; Casaccia-Bonnefil, Patrizia; Jahn, Olaf; Nave, Klaus-Armin

    2009-01-01

    Mice lacking the expression of proteolipid protein (PLP)/DM20 in oligodendrocytes provide a genuine model for spastic paraplegia (SPG-2). Their axons are well myelinated but exhibit impaired axonal transport and progressive degeneration, which is difficult to attribute to the absence of a single myelin protein. We hypothesized that secondary molecular changes in PLPnull myelin contribute to the loss of PLP/DM20-dependent neuroprotection and provide more insight into glia-axonal interactions in this disease model. By gel-based proteome analysis, we identified >160 proteins in purified myelin membranes, which allowed us to systematically monitor the CNS myelin proteome of adult PLPnull mice, before the onset of disease. We identified three proteins of the septin family to be reduced in abundance, but the nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase sirtuin 2 (SIRT2) was virtually absent. SIRT2 is expressed throughout the oligodendrocyte lineage, and immunoelectron microscopy revealed its association with myelin. Loss of SIRT2 in PLPnull was posttranscriptional, suggesting that PLP/DM20 is required for its transport into the myelin compartment. Because normal SIRT2 activity is controlled by the NAD+/NADH ratio, its function may be coupled to the axo-glial metabolism and the long-term support of axons by oligodendrocytes. PMID:17634366

  9. Axo-Glia Interaction Preceding CNS Myelination Is Regulated by Bidirectional Eph-Ephrin Signaling

    PubMed Central

    Linneberg, Cecilie; Harboe, Mette

    2015-01-01

    In the central nervous system, myelination of axons is required to ensure fast saltatory conduction and for survival of neurons. However, not all axons are myelinated, and the molecular mechanisms involved in guiding the oligodendrocyte processes toward the axons to be myelinated are not well understood. Only a few negative or positive guidance clues that are involved in regulating axo-glia interaction prior to myelination have been identified. One example is laminin, known to be required for early axo-glia interaction, which functions through α6β1 integrin. Here, we identify the Eph-ephrin family of guidance receptors as novel regulators of the initial axo-glia interaction, preceding myelination. We demonstrate that so-called forward and reverse signaling, mediated by members of both Eph and ephrin subfamilies, has distinct and opposing effects on processes extension and myelin sheet formation. EphA forward signaling inhibits oligodendrocyte process extension and myelin sheet formation, and blocking of bidirectional signaling through this receptor enhances myelination. Similarly, EphB forward signaling also reduces myelin membrane formation, but in contrast to EphA forward signaling, this occurs in an integrin-dependent manner, which can be reversed by overexpression of a constitutive active β1-integrin. Furthermore, ephrin-B reverse signaling induced by EphA4 or EphB1 enhances myelin sheet formation. Combined, this suggests that the Eph-ephrin receptors are important mediators of bidirectional signaling between axons and oligodendrocytes. It further implies that balancing Eph-ephrin forward and reverse signaling is important in the selection process of axons to be myelinated. PMID:26354550

  10. Axo-Glia Interaction Preceding CNS Myelination Is Regulated by Bidirectional Eph-Ephrin Signaling.

    PubMed

    Linneberg, Cecilie; Harboe, Mette; Laursen, Lisbeth S

    2015-01-01

    In the central nervous system, myelination of axons is required to ensure fast saltatory conduction and for survival of neurons. However, not all axons are myelinated, and the molecular mechanisms involved in guiding the oligodendrocyte processes toward the axons to be myelinated are not well understood. Only a few negative or positive guidance clues that are involved in regulating axo-glia interaction prior to myelination have been identified. One example is laminin, known to be required for early axo-glia interaction, which functions through α6β1 integrin. Here, we identify the Eph-ephrin family of guidance receptors as novel regulators of the initial axo-glia interaction, preceding myelination. We demonstrate that so-called forward and reverse signaling, mediated by members of both Eph and ephrin subfamilies, has distinct and opposing effects on processes extension and myelin sheet formation. EphA forward signaling inhibits oligodendrocyte process extension and myelin sheet formation, and blocking of bidirectional signaling through this receptor enhances myelination. Similarly, EphB forward signaling also reduces myelin membrane formation, but in contrast to EphA forward signaling, this occurs in an integrin-dependent manner, which can be reversed by overexpression of a constitutive active β1-integrin. Furthermore, ephrin-B reverse signaling induced by EphA4 or EphB1 enhances myelin sheet formation. Combined, this suggests that the Eph-ephrin receptors are important mediators of bidirectional signaling between axons and oligodendrocytes. It further implies that balancing Eph-ephrin forward and reverse signaling is important in the selection process of axons to be myelinated. PMID:26354550

  11. TAPP1 inhibits the differentiation of oligodendrocyte precursor cells via suppressing the Mek/Erk pathway.

    PubMed

    Chen, Yidan; Mei, Ruyi; Teng, Peng; Yang, Aifen; Hu, Xuemei; Zhang, Zunyi; Qiu, Mengsheng; Zhao, Xiaofeng

    2015-10-01

    Oligodendrocytes (OLs) are glial cells that form myelin sheaths around axons in the central nervous system (CNS). Loss of the myelin sheath in demyelinating and neurodegenerative diseases can lead to severe impairment of movement. Understanding the extracellular signals and intracellular factors that regulate OL differentiation and myelination during development can help to develop novel strategies for enhancing myelin repair in neurological disorders. Here, we report that TAPP1 was selectively expressed in differentiating OL precursor cells (OPCs). TAPP1 knockdown promoted OL differentiation and myelin gene expression in culture. Conversely, over-expression of TAPP1 in immature OPCs suppressed their differentiation. Moreover, TAPP1 inhibition in OPCs altered the expression of Erk1/2 but not AKT. Taken together, our results identify TAPP1 as an important negative regulator of OPC differentiation through the Mek/Erk signaling pathway. PMID:26242484

  12. SomethiNG 2 talk about-Transcriptional regulation in embryonic and adult oligodendrocyte precursors.

    PubMed

    Küspert, Melanie; Wegner, Michael

    2016-05-01

    Glial cells that express the chondroitin sulfate proteoglycan NG2 represent an inherently heterogeneous population. These so-called NG2-glia are present during development and in the adult CNS, where they are referred to as embryonic oligodendrocyte precursors and adult NG2-glia, respectively. They give rise to myelinating oligodendrocytes at all times of life. Over the years much has been learnt about the transcriptional network in embryonic oligodendrocyte precursors, and several transcription factors from the HLH, HMG-domain, zinc finger and homeodomain protein families have been identified as main constituents. Much less is known about the corresponding network in adult NG2-glia. Here we summarize and discuss current knowledge on functions of each of these transcription factor families in NG2-glia, and where possible compare transcriptional regulation in embryonic oligodendrocyte precursors and adult NG2-glia. This article is part of a Special Issue entitled SI:NG2-glia (Invited only). PMID:26232072

  13. Spatiotemporal ablation of CXCR2 on oligodendrocyte lineage cells

    PubMed Central

    Spangler, Lisa C.; Prager, Briana; Benson, Bryan; Hu, BingQing; Shi, Samuel; Love, Anna; Zhang, CunJin; Yu, Meigen; Cotleur, Anne C.

    2015-01-01

    Background: Residual CXCR2 expression on CNS cells in Cxcr2+/−→Cxcr2−/− chimeric animals slowed remyelination after both experimental autoimmune encephalomyelitis and cuprizone-induced demyelination. Methods: We generated Cxcr2fl/−:PLPCre-ER(T) mice enabling an inducible, conditional deletion of Cxcr2 on oligodendrocyte lineage cells of the CNS. Cxcr2fl/−:PLPCre-ER(T) mice were evaluated in 2 demyelination/remyelination models: cuprizone-feeding and in vitro lysophosphatidylcholine (LPC) treatment of cerebellar slice cultures. Results: Cxcr2fl/−:PLPCre-ER(T)+ (termed Cxcr2-cKO) mice showed better myelin repair 4 days after LPC-induced demyelination of cerebellar slice cultures. Cxcr2-cKOs also displayed enhanced hippocampal remyelination after a 2-week recovery from 6-week cuprizone feeding. Conclusion: Using 2 independent demyelination/remyelination models, our data document enhanced myelin repair in Cxcr2-cKO mice, consistent with the data obtained from radiation chimerism studies of germline CXCR2. Further experiments are appropriate to explore how CXCR2 function in the oligodendrocyte lineage accelerates myelin repair. PMID:26668819

  14. Strategies for Protecting Oligodendrocytes and Enhancing Remyelination in Multiple Sclerosis

    PubMed Central

    RODGERS, JANE M.; ROBINSON, ANDREW P.; MILLER, STEPHEN D.

    2014-01-01

    Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS) characterized by encephalitogenic leukocyte infiltration and multifocal plaques of demyelination. Patients present with debilitating clinical sequelae including motor, sensory, and cognitive deficits. For the past 30 years, immune modulating treatments have entered the marketplace and continue to improve in limiting the frequency and severity of relapses, but no cure has been found and no drug has successfully stopped chronic progressive disease. Recent work focusing on the oligodendrocyte, the myelin-producing cell, has provided needed insight into the process of demyelination, the spontaneous ability of the CNS to regenerate, and the inevitable failure of remyelination. From this a number of promising molecular targets have been identified to protect oligodendrocytes and promote remyelination. Combining immunomodulatory therapy with strategies to protect oligodendrocytes from further degeneration and enhance remyelination presents a very real means to improve clinical outcome for chronic progressive patients in the near future. Here we lay out a combination therapy approach to treating MS and survey the current literature on promising drug candidates potentially capable of mediating oligodendrocyte protection and enhancing remyelination. PMID:23911232

  15. Selective and compartmentalized myelin expression of HspB5.

    PubMed

    Quraishe, S; Wyttenbach, A; Matinyarare, N; Perry, V H; Fern, R; O'Connor, V

    2016-03-01

    In the present study, we reveal myelin-specific expression and targeting of mRNA and biochemical pools of HspB5 in the mouse CNS. Our observations are based on in situ hybridization, electron microscopy and co-localization with 2',3'-Cyclic-Nucleotide 3'-Phosphodiesterase (CNPase), reinforcing this myelin-selective expression. HspB5 mRNA might be targeted to these structures based on its presence in discrete clusters resembling RNA granules and the presence of a putative RNA transport signal. Further, sub-cellular fractionation of myelin membranes reveals a distinct sub-compartment-specific association and detergent solubility of HspB5. This is akin to other abundant myelin proteins and is consistent with HspB5's association with cytoskeletal/membrane assemblies. Oligodendrocytes have a pivotal role in supporting axonal function via generating and segregating the ensheathing myelin. This specialization places extreme structural and metabolic demands on this glial cell type. Our observations place HspB5 in oligodendrocytes which may require selective and specific chaperone capabilities to maintain normal function and neuronal support. PMID:26718604

  16. Lesioned corticospinal tract axons regenerate in myelin-free rat spinal cord

    SciTech Connect

    Savio, T.; Schwab, M.E. )

    1990-06-01

    In the adult central nervous system (CNS) of higher vertebrates lesioned axons seemed unable to regenerate and reach their former target regions due to influences of the CNS microenvironment. Evidence from in vitro and biochemical experiments has demonstrated the presence of inhibitory substrate components in CNS tissue, in particular in white matter. These CNS components, which strongly inhibit neurite growth, were identified as minor membrane proteins of defined molecular mass (35 and 250 kDa) in oligodendrocyte membranes and CNS myelin. Oligodendrocyte development and myelin formation can be prevented by x-irradiation of newborn rats. Here we show that in myelin-free spinal cords cortico-spinal tract fibers transected at 2 weeks of age show reelongation of many millimeters within 2-3 weeks after the lesion. In normally myelinated controls, regenerative sprouts grew less than 1.7 mm caudal to the lesion.

  17. Early loss of oligodendrocytes in human and experimental neuromyelitis optica lesions

    PubMed Central

    Wrzos, Claudia; Winkler, Anne; Metz, Imke; Kayser, Dieter M.; Thal, Dietmar R.; Wegner, Christiane; Brück, Wolfgang; Nessler, Stefan; Bennett, Jeffrey L.

    2014-01-01

    Neuromyelitis optica (NMO) is a chronic, mostly relapsing inflammatory demyelinating disease of the CNS characterized by serum anti-aquaporin 4 (AQP4) antibodies in the majority of patients. Anti-AQP4 antibodies derived from NMO patients target and deplete astrocytes in experimental models when co-injected with complement. However, the time course and mechanisms of oligodendrocyte loss and demyelination and the fate of oligodendrocyte precursor cells (OPC) have not been examined in detail. Also, no studies regarding astrocyte repopulation of experimental NMO lesions have been reported. We utilized two rat models using either systemic transfer or focal intracerebral injection of recombinant human anti-AQP4 antibodies to generate NMO-like lesions. Time-course experiments were performed to examine oligodendroglial and astroglial damage and repair. In addition, oligodendrocyte pathology was studied in early human NMO lesions. Apart from early complement-mediated astrocyte destruction, we observed a prominent, very early loss of oligodendrocytes and oligodendrocyte precursor cells (OPCs) as well as a delayed loss of myelin. Astrocyte repopulation of focal NMO lesions was already substantial after 1 week. Olig2-positive OPCs reappeared before NogoA-positive, mature oligodendrocytes. Thus, using two experimental models that closely mimic the human disease, our study demonstrates that oligodendrocyte and OPC loss is an extremely early feature in the formation of human and experimental NMO lesions and leads to subsequent, delayed demyelination, highlighting an important difference in the pathogenesis of MS and NMO. PMID:24292009

  18. ER Chaperone BiP/GRP78 Is Required for Myelinating Cell Survival and Provides Protection during Experimental Autoimmune Encephalomyelitis.

    PubMed

    Hussien, Yassir; Podojil, Joseph R; Robinson, Andrew P; Lee, Amy S; Miller, Steven D; Popko, Brian

    2015-12-01

    Myelinating cells synthesize large amounts of membrane protein through the secretory pathway, which makes these cells particularly sensitive to perturbations of the endoplasmic reticulum (ER). Ig binding protein (BiP), also known as glucose-regulated protein 78 (GRP78), is a critical ER chaperone that also plays a pivotal role in controlling the cellular response to ER stress. To examine the potential importance of BiP to myelinating cells, we used a conditional knock-out approach to BiP gene inactivation in oligodendrocytes during development, in adulthood, and in response to experimental autoimmune encephalomyelitis (EAE), an animal model of the inflammatory demyelinating disorder multiple sclerosis (MS). During development, mice lacking functional BiP gene expression in oligodendrocytes developed tremors and ataxia and died before reaching maturity. When BiP gene inactivation in oligodendrocytes was initiated in adulthood, the mice displayed severe neurological symptoms including tremors and hind-limb paralysis. The inactivation of BiP in oligodendrocytes during development or in adulthood resulted in oligodendrocyte loss and corresponding severe myelin abnormalities. Mice heterozygous for the oligodendrocyte-specific inactivation of BiP, which were phenotypically normal without evidence of neuropathology, displayed an exacerbated response to EAE that correlated with an increased loss of oligodendrocytes. Furthermore, mice in which the BiP gene was specifically inactivated in developing Schwann cells displayed tremor that progressed to hindlimb paralysis, which correlated with diminished numbers of myelinating Schwann cells and severe PNS hypomyelination. These studies demonstrate that BiP is critical for myelinating cell survival and contributes to the protective response of oligodendrocyte against inflammatory demyelination. PMID:26631473

  19. Myelin damage and repair in pathologic CNS: challenges and prospects

    PubMed Central

    Alizadeh, Arsalan; Dyck, Scott M.; Karimi-Abdolrezaee, Soheila

    2015-01-01

    Injury to the central nervous system (CNS) results in oligodendrocyte cell death and progressive demyelination. Demyelinated axons undergo considerable physiological changes and molecular reorganizations that collectively result in axonal dysfunction, degeneration and loss of sensory and motor functions. Endogenous adult oligodendrocyte precursor cells and neural stem/progenitor cells contribute to the replacement of oligodendrocytes, however, the extent and quality of endogenous remyelination is suboptimal. Emerging evidence indicates that optimal remyelination is restricted by multiple factors including (i) low levels of factors that promote oligodendrogenesis; (ii) cell death among newly generated oligodendrocytes, (iii) inhibitory factors in the post-injury milieu that impede remyelination, and (iv) deficient expression of key growth factors essential for proper re-construction of a highly organized myelin sheath. Considering these challenges, over the past several years, a number of cell-based strategies have been developed to optimize remyelination therapeutically. Outcomes of these basic and preclinical discoveries are promising and signify the importance of remyelination as a mechanism for improving functions in CNS injuries. In this review, we provide an overview on: (1) the precise organization of myelinated axons and the reciprocal axo-myelin interactions that warrant properly balanced physiological activities within the CNS; (2) underlying cause of demyelination and the structural and functional consequences of demyelination in axons following injury and disease; (3) the endogenous mechanisms of oligodendrocyte replacement; (4) the modulatory role of reactive astrocytes and inflammatory cells in remyelination; and (5) the current status of cell-based therapies for promoting remyelination. Careful elucidation of the cellular and molecular mechanisms of demyelination in the pathologic CNS is a key to better understanding the impact of remyelination for

  20. Cystine/glutamate antiporter blockage induces myelin degeneration.

    PubMed

    Soria, Federico N; Zabala, Alazne; Pampliega, Olatz; Palomino, Aitor; Miguelez, Cristina; Ugedo, Luisa; Sato, Hideyo; Matute, Carlos; Domercq, María

    2016-08-01

    The cystine/glutamate antiporter is a membrane transport system responsible for the uptake of extracellular cystine and release of intracellular glutamate. It is the major source of cystine in most cells, and a key regulator of extrasynaptic glutamate in the CNS. Because cystine is the limiting factor in the biosynthesis of glutathione, and glutamate is the most abundant neurotransmitter, the cystine/glutamate antiporter is a central player both in antioxidant defense and glutamatergic signaling, two events critical to brain function. However, distribution of cystine/glutamate antiporter in CNS has not been well characterized. Here, we analyzed expression of the catalytic subunit of the cystine/glutamate antiporter, xCT, by immunohistochemistry in histological sections of the forebrain and spinal cord. We detected labeling in neurons, oligodendrocytes, microglia, and oligodendrocyte precursor cells, but not in GFAP(+) astrocytes. In addition, we examined xCT expression and function by qPCR and cystine uptake in primary rat cultures of CNS, detecting higher levels of antiporter expression in neurons and oligodendrocytes. Chronic inhibition of cystine/glutamate antiporter caused high toxicity to cultured oligodendrocytes. In accordance, chronic blockage of cystine/glutamate antiporter as well as glutathione depletion caused myelin disruption in organotypic cerebellar slices. Finally, mice chronically treated with sulfasalazine, a cystine/glutamate antiporter inhibitor, showed a reduction in the levels of myelin and an increase in the myelinated fiber g-ratio. Together, these results reveal that cystine/glutamate antiporter is expressed in oligodendrocytes, where it is a key factor to the maintenance of cell homeostasis. GLIA 2016. GLIA 2016;64:1381-1395. PMID:27247047

  1. NF-κB signaling regulates myelination in the CNS

    PubMed Central

    Blank, Thomas; Prinz, Marco

    2014-01-01

    Besides myelination of neuronal axons by oligodendrocytes to facilitate propagation of action potentials, oligodendrocytes also support axon survival and function. A key transcription factor involved in these processes is nuclear factor-κB (NF-κB), a hetero or homodimer of the Rel family of proteins, including p65, c-Rel, RelB, p50, and p52. Under unstimulated, NF-κB remains inactive in the cytoplasm through interaction with NF-κB inhibitors (IκBs). Upon activation of NF-κB the cytoplasmic IκBs gets degradated, allowing the translocation of NF-κB into the nucleus where the dimer binds to the κB consensus DNA sequence and regulates gene transcription. In this review we describe how oligodendrocytes are, directly or indirectly via neighboring cells, regulated by NF-κB signaling with consequences for innate and adaptive immunity and for regulation of cell apoptosis and survival. PMID:24904273

  2. Translational Control of Myelin Basic Protein Expression by ERK2 MAP Kinase Regulates Timely Remyelination in the Adult Brain

    PubMed Central

    Michel, Kelly; Zhao, Tianna; Karl, Molly; Lewis, Katherine

    2015-01-01

    Successful myelin repair in the adult CNS requires the robust and timely production of myelin proteins to generate new myelin sheaths. The underlying regulatory mechanisms and complex molecular basis of myelin regeneration, however, remain poorly understood. Here, we investigate the role of ERK MAP kinase signaling in this process. Conditional deletion of Erk2 from cells of the oligodendrocyte lineage resulted in delayed remyelination following demyelinating injury to the adult mouse corpus callosum. The delayed repair occurred as a result of a specific deficit in the translation of the major myelin protein, MBP. In the absence of ERK2, activation of the ribosomal protein S6 kinase (p70S6K) and its downstream target, ribosomal protein S6 (S6RP), was impaired at a critical time when premyelinating oligodendrocytes were transitioning to mature cells capable of generating new myelin sheaths. Thus, we have described an important link between the ERK MAP kinase signaling cascade and the translational machinery specifically in remyelinating oligodendrocytes in vivo. These results suggest an important role for ERK2 in the translational control of MBP, a myelin protein that appears critical for ensuring the timely generation of new myelin sheaths following demyelinating injury in the adult CNS. PMID:25995471

  3. Translational control of myelin basic protein expression by ERK2 MAP kinase regulates timely remyelination in the adult brain.

    PubMed

    Michel, Kelly; Zhao, Tianna; Karl, Molly; Lewis, Katherine; Fyffe-Maricich, Sharyl L

    2015-05-20

    Successful myelin repair in the adult CNS requires the robust and timely production of myelin proteins to generate new myelin sheaths. The underlying regulatory mechanisms and complex molecular basis of myelin regeneration, however, remain poorly understood. Here, we investigate the role of ERK MAP kinase signaling in this process. Conditional deletion of Erk2 from cells of the oligodendrocyte lineage resulted in delayed remyelination following demyelinating injury to the adult mouse corpus callosum. The delayed repair occurred as a result of a specific deficit in the translation of the major myelin protein, MBP. In the absence of ERK2, activation of the ribosomal protein S6 kinase (p70S6K) and its downstream target, ribosomal protein S6 (S6RP), was impaired at a critical time when premyelinating oligodendrocytes were transitioning to mature cells capable of generating new myelin sheaths. Thus, we have described an important link between the ERK MAP kinase signaling cascade and the translational machinery specifically in remyelinating oligodendrocytes in vivo. These results suggest an important role for ERK2 in the translational control of MBP, a myelin protein that appears critical for ensuring the timely generation of new myelin sheaths following demyelinating injury in the adult CNS. PMID:25995471

  4. Dietary triheptanoin rescues oligodendrocyte loss, dysmyelination and motor function in the nur7 mouse model of Canavan disease.

    PubMed

    Francis, Jeremy S; Markov, Vladimir; Leone, Paola

    2014-05-01

    The inherited pediatric leukodystrophy Canavan disease is characterized by dysmyelination and severe spongiform degeneration, and is currently refractory to treatment. A definitive understanding of core disease mechanisms is lacking, but pathology is believed to result at least in part compromised fatty acid synthesis during myelination. Recent evidence generated in an animal model suggests that the breakdown of N-acetylaspartate metabolism in CD results in a heightened coupling of fatty acid synthesis to oligodendrocyte oxidative metabolism during the early stages of myelination, thereby causing acute oxidative stress. We present here the results of a dietary intervention designed to support oxidative integrity during developmental myelination in the nur7 mouse model of Canavan disease. Provision of the odd carbon triglyceride triheptanoin to neonatal nur7 mice reduced oxidative stress, promoted long-term oligodendrocyte survival, and increased myelin in the brain. Improvements in oligodendrocyte survival and myelination were associated with a highly significant reduction in spongiform degeneration and improved motor function in triheptanoin treated mice. Initiation of triheptanoin treatment in older animals resulted in markedly more modest effects on these same pathological indices, indicating a window of therapeutic intervention that corresponds with developmental myelination. These results support the targeting of oxidative integrity at early stages of Canavan disease, and provide a foundation for the clinical development of a non-invasive dietary triheptanoin treatment regimen. PMID:24288037

  5. Organization and maintenance of molecular domains in myelinated axons.

    PubMed

    Buttermore, Elizabeth D; Thaxton, Courtney L; Bhat, Manzoor A

    2013-05-01

    Over a century ago, Ramon y Cajal first proposed the idea of a directionality involved in nerve conduction and neuronal communication. Decades later, it was discovered that myelin, produced by glial cells, insulated axons with periodic breaks where nodes of Ranvier (nodes) form to allow for saltatory conduction. In the peripheral nervous system (PNS), Schwann cells are the glia that can either individually myelinate the axon from one neuron or ensheath axons of many neurons. In the central nervous system (CNS), oligodendrocytes are the glia that myelinate axons from different neurons. Review of more recent studies revealed that this myelination created polarized domains adjacent to the nodes. However, the molecular mechanisms responsible for the organization of axonal domains are only now beginning to be elucidated. The molecular domains in myelinated axons include the axon initial segment (AIS), where various ion channels are clustered and action potentials are initiated; the node, where sodium channels are clustered and action potentials are propagated; the paranode, where myelin loops contact with the axolemma; the juxtaparanode (JXP), where delayed-rectifier potassium channels are clustered; and the internode, where myelin is compactly wrapped. Each domain contains a unique subset of proteins critical for the domain's function. However, the roles of these proteins in axonal domain organization are not fully understood. In this review, we highlight recent advances on the molecular nature and functions of some of the components of each axonal domain and their roles in axonal domain organization and maintenance for proper neuronal communication. PMID:23404451

  6. Panglial gap junctional communication is essential for maintenance of myelin in the CNS.

    PubMed

    Tress, Oliver; Maglione, Marta; May, Dennis; Pivneva, Tatjyana; Richter, Nadine; Seyfarth, Julia; Binder, Sonja; Zlomuzica, Armin; Seifert, Gerald; Theis, Martin; Dere, Ekrem; Kettenmann, Helmut; Willecke, Klaus

    2012-05-30

    In this study, we have investigated the contribution of oligodendrocytic connexin47 (Cx47) and astrocytic Cx30 to panglial gap junctional networks as well as myelin maintenance and function by deletion of both connexin coding DNAs in mice. Biocytin injections revealed complete disruption of oligodendrocyte-to-astrocyte coupling in the white matter of 10- to 15-d-old Cx30/Cx47 double-deficient mice, while oligodendrocyte-to-oligodendrocyte coupling was maintained. There were no quantitative differences regarding cellular networks in acute brain slices obtained from Cx30/Cx47 double-null mice and control littermates, probably caused by the upregulation of oligodendrocytic Cx32 in Cx30/Cx47 double-deficient mice. We observed early onset myelin pathology, and ∼40% of Cx30/Cx47 double-deficient animals died within 42 to 90 d after birth, accompanied by severe motor impairments. Histological and ultrastructural analyses revealed severe vacuolization and myelination defects in all white matter tracts of the CNS. Furthermore, Cx30/Cx47 double-deficient mice exhibited a decreased number of oligodendrocytes, severe astrogliosis, and microglial activation in white matter tracts. Although less affected concerning motor impairment, surviving double-knock-out (KO) mice showed behavioral alterations in the open field and in the rotarod task. Vacuole formation and thinner myelin sheaths were evident also with adult surviving double-KO mice. Since interastrocytic coupling due to Cx43 expression and interoligodendrocytic coupling because of Cx32 expression are still maintained, Cx30/Cx47 double-deficient mice demonstrate the functional role of both connexins for interastrocytic, interoligodendrocytic, and panglial coupling, and show that both connexins are required for maintenance of myelin. PMID:22649229

  7. Aspirin Promotes Oligodendrocyte Precursor Cell Proliferation and Differentiation after White Matter Lesion

    PubMed Central

    Chen, Jing; Zuo, Shilun; Wang, Jing; Huang, Jian; Zhang, Xiao; Liu, Yang; Zhang, Yunxia; Zhao, Jun; Han, Junliang; Xiong, Lize; Shi, Ming; Liu, Zhirong

    2014-01-01

    Cerebral white matter lesion (WML) is one of the main causes for cognitive impairment and is often caused by chronic cerebral hypoperfusion. A line of evidence has shown that aspirin has neuroprotective effects and produces some benefits in long-term outcome and survival for ischemic stroke patients. However, whether aspirin exerts a protective effect against WML is still largely unknown. Here, we showed that aspirin could promote oligodendrocyte precursor cell (OPC) proliferation and differentiation into oligodendrocytes after WML. Male Sprague-Dawley rats were subjected to permanent bilateral common carotid artery occlusion, a well-established model for WML. Four weeks later, Morris water maze test showed an impairment of learning and memory ability of rat while aspirin treatment improved behavioral performance. Low dose of aspirin (25 mg/kg) was found to elevate the number of OPCs while relatively high doses (100–200 mg/kg) increased that of oligodendrocytes, and ameliorated WML-induced the thinning of myelin, as revealed by the electron microscope. Similarly, our in vitro study also showed that relatively low and high doses of aspirin enhanced OPC proliferation and differentiation into oligodendrocytes, respectively. Furthermore, we revealed that aspirin enhanced extracellular signal-related kinase (ERK) but inhibited RhoA activities. In summary, we provided the first evidence that aspirin can promote oligodendrogenesis and oligodendrocyte myelination after WML, which may involve ERK and RhoA pathways. PMID:24478700

  8. miRNAs As Emerging Regulators of Oligodendrocyte Development and Differentiation

    PubMed Central

    Galloway, Dylan A.; Moore, Craig S.

    2016-01-01

    Chronic demyelination is a hallmark of neurological disorders such as multiple sclerosis (MS) and several leukodystrophies. In the central nervous system (CNS), remyelination is a regenerative process that is often inadequate during these pathological states. In the MS context, in situ evidence suggests that remyelination is mediated by populations of oligodendrocyte progenitor cells (OPCs) that proliferate, migrate, and differentiate into mature, myelin-producing oligodendrocytes at sites of demyelinated lesions. The molecular programming of OPCs into mature oligodendrocytes is governed by a myriad of complex intracellular signaling pathways that modulate this process. Recent research has demonstrated the importance of specific and short non-coding RNAs, known as microRNAs (miRNAs), in regulating OPC differentiation and remyelination. Fortunately, it may be possible to take advantage of numerous developmental studies (both human and rodent) that have previously characterized miRNA expression profiles from the early neural progenitor cell to the late myelin-producing oligodendrocyte. Here we review much of the work to date and discuss the impact of miRNAs on OPC and oligodendrocyte biology. Additionally, we consider the potential for miRNA-mediated therapy in the context of remyelination and brain repair. PMID:27379236

  9. CSF myelin basic protein

    MedlinePlus

    CSF myelin basic protein is a test to measure the level of myelin basic protein (MBP) in the cerebrospinal fluid (CSF). The CSF ... less than 4 ng/mL of myelin basic protein in the CSF. Normal value ranges may vary ...

  10. Galactosphingolipids and axono-glial interaction in myelin of the central nervous system.

    PubMed

    Bosio, A; Büssow, H; Adam, J; Stoffel, W

    1998-05-01

    The myelin of central and peripheral nervous system of UDP-galactose-ceramide galactosyltransferase deficient mice (cgt-/-) is completely depleted of its major lipid constituents, galactocerebrosides and sulfatides. The deficiency of these glycolipids affects the biophysical properties of the myelin sheath and causes the loss of the rapid saltatory conduction velocity of myelinated axons. With the onset of myelination, null mutant cgt-/- mice develop fatal neurological defects. CNS and PNS analysis of cgt-/- mice revealed (1) hypomyelination of axons of the spinal cord and optic nerves, but no apoptosis of oligodendrocytes, (2) redundant myelin in younger mice leading to vacuolated nerve fibers in cgt-/- mice, (3) the occurrence of multiple myelinated CNS axons, and (4) severely distorted lateral loops in CNS paranodes. The loss of saltatory conduction is not associated with a randomization of voltage-gated sodium channels in the axolemma of PNS fibers. We conclude that cerebrosides (GalC) and sulfatides (sGalC) play a major role in CNS axono-glial interaction. A close axono-glial contact is not a prerequisite for the spiraling and compaction process of myelin. Axonal sodium channels remain clustered at the nodes of Ranvier independent of the change in the physical properties of myelin membrane devoid of galactosphingolipids. Increased intracellular concentrations of free ceramides do not trigger apoptosis of oligodendrocytes. PMID:9560463

  11. Restoration of Oligodendrocyte Pools in a Mouse Model of Chronic Cerebral Hypoperfusion

    PubMed Central

    McQueen, Jamie; Reimer, Michell M.; Holland, Philip R.; Manso, Yasmina; McLaughlin, Mark; Fowler, Jill H.; Horsburgh, Karen

    2014-01-01

    Chronic cerebral hypoperfusion, a sustained modest reduction in cerebral blood flow, is associated with damage to myelinated axons and cognitive decline with ageing. Oligodendrocytes (the myelin producing cells) and their precursor cells (OPCs) may be vulnerable to the effects of hypoperfusion and in some forms of injury OPCs have the potential to respond and repair damage by increased proliferation and differentiation. Using a mouse model of cerebral hypoperfusion we have characterised the acute and long term responses of oligodendrocytes and OPCs to hypoperfusion in the corpus callosum. Following 3 days of hypoperfusion, numbers of OPCs and mature oligodendrocytes were significantly decreased compared to controls. However following 1 month of hypoperfusion, the OPC pool was restored and increased numbers of oligodendrocytes were observed. Assessment of proliferation using PCNA showed no significant differences between groups at either time point but showed reduced numbers of proliferating oligodendroglia at 3 days consistent with the loss of OPCs. Cumulative BrdU labelling experiments revealed higher numbers of proliferating cells in hypoperfused animals compared to controls and showed a proportion of these newly generated cells had differentiated into oligodendrocytes in a subset of animals. Expression of GPR17, a receptor important for the regulation of OPC differentiation following injury, was decreased following short term hypoperfusion. Despite changes to oligodendrocyte numbers there were no changes to the myelin sheath as revealed by ultrastructural assessment and fluoromyelin however axon-glial integrity was disrupted after both 3 days and 1 month hypoperfusion. Taken together, our results demonstrate the initial vulnerability of oligodendroglial pools to modest reductions in blood flow and highlight the regenerative capacity of these cells. PMID:24498301

  12. Individual Neuronal Subtypes Exhibit Diversity in CNS Myelination Mediated by Synaptic Vesicle Release.

    PubMed

    Koudelka, Sigrid; Voas, Matthew G; Almeida, Rafael G; Baraban, Marion; Soetaert, Jan; Meyer, Martin P; Talbot, William S; Lyons, David A

    2016-06-01

    Regulation of myelination by oligodendrocytes in the CNS has important consequences for higher-order nervous system function (e.g., [1-4]), and there is growing consensus that neuronal activity regulates CNS myelination (e.g., [5-9]) through local axon-oligodendrocyte synaptic-vesicle-release-mediated signaling [10-12]. Recent analyses have indicated that myelination along axons of distinct neuronal subtypes can differ [13, 14], but it is not known whether regulation of myelination by activity is common to all neuronal subtypes or only some. This limits insight into how specific neurons regulate their own conduction. Here, we use a novel fluorescent fusion protein reporter to study myelination along the axons of distinct neuronal subtypes over time in zebrafish. We find that the axons of reticulospinal and commissural primary ascending (CoPA) neurons are among the first myelinated in the zebrafish CNS. To investigate how activity regulates myelination by different neuronal subtypes, we express tetanus toxin (TeNT) in individual reticulospinal or CoPA neurons to prevent synaptic vesicle release. We find that the axons of individual tetanus toxin expressing reticulospinal neurons have fewer myelin sheaths than controls and that their myelin sheaths are 50% shorter than controls. In stark contrast, myelination along tetanus-toxin-expressing CoPA neuron axons is entirely normal. These results indicate that while some neuronal subtypes modulate myelination by synaptic vesicle release to a striking degree in vivo, others do not. These data have implications for our understanding of how different neurons regulate myelination and thus their own function within specific neuronal circuits. PMID:27161502

  13. Formation of compact myelin is required for maturation of the axonal cytoskeleton

    NASA Technical Reports Server (NTRS)

    Brady, S. T.; Witt, A. S.; Kirkpatrick, L. L.; de Waegh, S. M.; Readhead, C.; Tu, P. H.; Lee, V. M.

    1999-01-01

    Although traditional roles ascribed to myelinating glial cells are structural and supportive, the importance of compact myelin for proper functioning of the nervous system can be inferred from mutations in myelin proteins and neuropathologies associated with loss of myelin. Myelinating Schwann cells are known to affect local properties of peripheral axons (de Waegh et al., 1992), but little is known about effects of oligodendrocytes on CNS axons. The shiverer mutant mouse has a deletion in the myelin basic protein gene that eliminates compact myelin in the CNS. In shiverer mice, both local axonal features like phosphorylation of cytoskeletal proteins and neuronal perikaryon functions like cytoskeletal gene expression are altered. This leads to changes in the organization and composition of the axonal cytoskeleton in shiverer unmyelinated axons relative to age-matched wild-type myelinated fibers, although connectivity and patterns of neuronal activity are comparable. Remarkably, transgenic shiverer mice with thin myelin sheaths display an intermediate phenotype indicating that CNS neurons are sensitive to myelin sheath thickness. These results indicate that formation of a normal compact myelin sheath is required for normal maturation of the neuronal cytoskeleton in large CNS neurons.

  14. Oligodendrocyte Lineage and Subventricular Zone Response to Traumatic Axonal Injury in the Corpus Callosum

    PubMed Central

    Sullivan, Genevieve M.; Mierzwa, Amanda J.; Kijpaisalratana, Naruchorn; Tang, *Haiying; Wang, Yong; Song, Sheng-Kwei; Selwyn, Reed

    2013-01-01

    Abstract Traumatic brain injury frequently causes traumatic axonal injury (TAI) in white matter tracts. Experimental TAI in the corpus callosum of adult mice was used to examine the effects on oligodendrocyte lineage cells and myelin in conjunction with neuroimaging. The injury targeted the corpus callosum over the subventricular zone, a source of neural stem/progenitor cells. Traumatic axonal injury was produced in the rostral body of the corpus callosum by impact onto the skull at the bregma. During the first week after injury, magnetic resonance diffusion tensor imaging showed that axial diffusivity decreased in the corpus callosum and that corresponding regions exhibited significant axon damage accompanied by hypertrophic microglia and reactive astrocytes. Oligodendrocyte progenitor proliferation increased in the subventricular zone and corpus callosum. Oligodendrocytes in the corpus callosum shifted toward upregulation of myelin gene transcription. Plp/CreERT:R26IAP reporter mice showed normal reporter labeling of myelin sheaths 0 to 2 days after injury but labeling was increased between 2 and 7 days after injury. Electron microscopy revealed axon degeneration, demyelination, and redundant myelin figures. These findings expand the cell types and responses to white matter injuries that inform diffusion tensor imaging evaluation and identify pivotal white matter changes after TAI that may affect axon vulnerability vs. recovery after brain injury. PMID:24226267

  15. Myelin management by the 18.5–kDa and 21.5–kDa classic myelin basic protein isoforms

    PubMed Central

    Harauz, George; Boggs, Joan M.

    2013-01-01

    The classic myelin basic protein (MBP) splice isoforms range in nominal molecular mass from 14 to 21.5 kDa, and arise from the gene in the oligodendrocyte lineage (Golli) in maturing oligodendrocytes. The 18.5-kDa isoform that predominates in adult myelin adheres the cytosolic surfaces of oligodendrocyte membranes together, and forms a two-dimensional molecular sieve restricting protein diffusion into compact myelin. However, this protein has additional roles including cytoskeletal assembly and membrane extension, binding to SH3-domains, participation in Fyn-mediated signaling pathways, sequestration of phosphoinositides, and maintenance of calcium homeostasis. Of the diverse post-translational modifications of this isoform, phosphorylation is the most dynamic, and modulates 18.5-kDa MBP’s protein-membrane and protein-protein interactions, indicative of a rich repertoire of functions. In developing and mature myelin, phosphorylation can result in microdomain or even nuclear targeting of the protein, supporting the conclusion that 18.5-kDa MBP has significant roles beyond membrane adhesion. The full-length, early-developmental 21.5-kDa splice isoform is predominantly karyophilic due to a non-traditional P-Y nuclear localization signal, with effects such as promotion of oligodendrocyte proliferation. We discuss in vitro and recent in vivo evidence for multifunctionality of these classic basic proteins of myelin, and argue for a systematic evaluation of the temporal and spatial distributions of these protein isoforms, and their modified variants, during oligodendrocyte differentiation. PMID:23398367

  16. Association of myelin peptide with vitamin D prevents autoimmune encephalomyelitis development.

    PubMed

    Mimura, L A N; Chiuso-Minicucci, F; Fraga-Silva, T F C; Zorzella-Pezavento, S F G; França, T G D; Ishikawa, L L W; Penitenti, M; Ikoma, M R V; Sartori, A

    2016-03-11

    Multiple sclerosis is a chronic, inflammatory and demyelinating disease of the central nervous system (CNS). As there is no cure for this disease, new therapeutic strategies and prophylactic measures are necessary. We recently described the therapeutic activity of the association between myelin oligodendrocyte glycoprotein peptide (MOG) and active vitamin D3 (VitD) against experimental autoimmune encephalomyelitis (EAE). The objective of this work was to evaluate the prophylactic potential of this association in EAE. C57BL/6 mice were vaccinated with MOG in the presence of VitD and then subjected to EAE induction. Animals were euthanized 7 and 19days after disease induction and the following parameters were evaluated: body weight, clinical score, inflammatory process in the CNS, amount of dendritic cells (DCs) and regulatory T cells in the spleen and cytokine production by spleen and CNS cell cultures. Vaccination with MOG associated with VitD determined a drastic reduction in clinical score, body weight loss, CNS inflammation, DCs maturation and also in the production of cytokines by CNS and spleen cell cultures. Collectively, our data indicate that this association prevents EAE development. A similar effect from specific self-antigens associated with VitD is expected in other autoimmune conditions and deserves to be experimentally appraised. PMID:26762804

  17. Schwann cell myelination.

    PubMed

    Salzer, James L

    2015-08-01

    Myelinated nerve fibers are essential for the rapid propagation of action potentials by saltatory conduction. They form as the result of reciprocal interactions between axons and Schwann cells. Extrinsic signals from the axon, and the extracellular matrix, drive Schwann cells to adopt a myelinating fate, whereas myelination reorganizes the axon for its role in conduction and is essential for its integrity. Here, we review our current understanding of the development, molecular organization, and function of myelinating Schwann cells. Recent findings into the extrinsic signals that drive Schwann cell myelination, their cognate receptors, and the downstream intracellular signaling pathways they activate will be described. Together, these studies provide important new insights into how these pathways converge to activate the transcriptional cascade of myelination and remodel the actin cytoskeleton that is critical for morphogenesis of the myelin sheath. PMID:26054742

  18. Inhibitors of myelination: ECM changes, CSPGs and PTPs

    PubMed Central

    Harlow, Danielle E.; Macklin, Wendy B.

    2014-01-01

    After inflammation-induced demyelination, such as in the disease multiple sclerosis, endogenous remyelination often fails. However, in animal models of demyelination induced with toxins, remyelination can be quite robust. A significant difference between inflammation-induced and toxin-induced demyelination is the response of local cells within the lesion, including astrocytes, oligodendrocytes, microglia/macrophages, and NG2+ cells, which respond to inflammatory stimuli with increased extracellular matrix (ECM) protein and chondroitin sulfate proteoglycan (CSPG) production and deposition. Here, we summarize current knowledge of ECM changes in demyelinating lesions, as well as oligodendrocyte responses to aberrant ECM proteins and CSPGs after various types of demyelinating insults. The discovery that CSPGs act through the receptor protein tyrosine phosphatase sigma (PTPσ) and the Rho-ROCK pathway to inhibit oligodendrocyte process extension and myelination, but not oligodendrocyte differentiation (Pendleton et al., Experimental Neurology (2013) vol. 247, pp. 113-121), highlights the need to better understand the ECM changes that accompany demyelination and their influence on oligodendrocytes and effective remyelination. PMID:24200549

  19. Elevated in vivo levels of a single transcription factor directly convert satellite glia into oligodendrocyte-like cells.

    PubMed

    Weider, Matthias; Wegener, Amélie; Schmitt, Christian; Küspert, Melanie; Hillgärtner, Simone; Bösl, Michael R; Hermans-Borgmeyer, Irm; Nait-Oumesmar, Brahim; Wegner, Michael

    2015-02-01

    Oligodendrocytes are the myelinating glia of the central nervous system and ensure rapid saltatory conduction. Shortage or loss of these cells leads to severe malfunctions as observed in human leukodystrophies and multiple sclerosis, and their replenishment by reprogramming or cell conversion strategies is an important research aim. Using a transgenic approach we increased levels of the transcription factor Sox10 throughout the mouse embryo and thereby prompted Fabp7-positive glial cells in dorsal root ganglia of the peripheral nervous system to convert into cells with oligodendrocyte characteristics including myelin gene expression. These rarely studied and poorly characterized satellite glia did not go through a classic oligodendrocyte precursor cell stage. Instead, Sox10 directly induced key elements of the regulatory network of differentiating oligodendrocytes, including Olig2, Olig1, Nkx2.2 and Myrf. An upstream enhancer mediated the direct induction of the Olig2 gene. Unlike Sox10, Olig2 was not capable of generating oligodendrocyte-like cells in dorsal root ganglia. Our findings provide proof-of-concept that Sox10 can convert conducive cells into oligodendrocyte-like cells in vivo and delineates options for future therapeutic strategies. PMID:25680202

  20. Elevated In Vivo Levels of a Single Transcription Factor Directly Convert Satellite Glia into Oligodendrocyte-like Cells

    PubMed Central

    Weider, Matthias; Wegener, Amélie; Schmitt, Christian; Küspert, Melanie; Hillgärtner, Simone; Bösl, Michael R.; Hermans-Borgmeyer, Irm; Nait-Oumesmar, Brahim; Wegner, Michael

    2015-01-01

    Oligodendrocytes are the myelinating glia of the central nervous system and ensure rapid saltatory conduction. Shortage or loss of these cells leads to severe malfunctions as observed in human leukodystrophies and multiple sclerosis, and their replenishment by reprogramming or cell conversion strategies is an important research aim. Using a transgenic approach we increased levels of the transcription factor Sox10 throughout the mouse embryo and thereby prompted Fabp7-positive glial cells in dorsal root ganglia of the peripheral nervous system to convert into cells with oligodendrocyte characteristics including myelin gene expression. These rarely studied and poorly characterized satellite glia did not go through a classic oligodendrocyte precursor cell stage. Instead, Sox10 directly induced key elements of the regulatory network of differentiating oligodendrocytes, including Olig2, Olig1, Nkx2.2 and Myrf. An upstream enhancer mediated the direct induction of the Olig2 gene. Unlike Sox10, Olig2 was not capable of generating oligodendrocyte-like cells in dorsal root ganglia. Our findings provide proof-of-concept that Sox10 can convert conducive cells into oligodendrocyte-like cells in vivo and delineates options for future therapeutic strategies. PMID:25680202

  1. Molecular mechanisms regulating myelination in the peripheral nervous system.

    PubMed

    Pereira, Jorge A; Lebrun-Julien, Frédéric; Suter, Ueli

    2012-02-01

    Glial cells and neurons are engaged in a continuous and highly regulated bidirectional dialog. A remarkable example is the control of myelination. Oligodendrocytes in the central nervous system (CNS) and Schwann cells (SCs) in the peripheral nervous system (PNS) wrap their plasma membranes around axons to organize myelinated nerve fibers that allow rapid saltatory conduction. The functionality of this system is critical, as revealed by numerous neurological diseases that result from deregulation of the system, including multiple sclerosis and peripheral neuropathies. In this review we focus on PNS myelination and present a conceptual framework that integrates crucial signaling mechanisms with basic SC biology. We will highlight signaling hubs and overarching molecular mechanisms, including genetic, epigenetic, and post-translational controls, which together regulate the interplay between SCs and axons, extracellular signals, and the transcriptional network. PMID:22192173

  2. Expression of myelin genes in the developing chick retina.

    PubMed

    Gotoh, Hitosh; Ueda, Takayuki; Uno, Aoi; Ohuchi, Hideyo; Ikenaka, Kazuhiro; Ono, Katsuhiko

    2011-12-01

    In submammalian animals including chicks, the retina contains oligodendrocytes (OLs), and axons in the optic fiber layer are wrapped with compact myelin within the retina; however, the expression of myelin genes in the chick retina has not been demonstrated yet. In the present study, we examined the expression of three myelin genes (proteolipid protein, PLP; myelin basic protein, MBP; cyclic nucleotide phosphodiesterase, CNP) and PLP in the developing chick retina, in comparison to the localization of Mueller cells. In situ hybridization demonstrated that all three myelin genes began to be expressed at E14 in the chick embryo retina. They are mostly restricted to the ganglion cell layer and the optic fiber layer, with a few exceptions in the inner nuclear layer where Mueller cells reside; however, PLP mRNA+ cells do not express glutamine synthetase, or vice versa. The present results elucidate that myelin genes are expressed only by OLs that are mostly localized in the innermost layer of the developing chick retina. PMID:21872683

  3. In vivo labeling of peroxisomes by photoconvertible mEos2 in myelinating glia of mice.

    PubMed

    Richert, Sarah; Kleinecke, Sandra; Günther, Jenniffer; Schaumburg, Florian; Edgar, Julia; Nienhaus, Gerd Ulrich; Nave, Klaus-Armin; Kassmann, Celia M

    2014-03-01

    Mutations of several genes encoding peroxisomal proteins have been associated with human diseases. Some of these display specific white matter abnormalities in the brain, although the affected proteins are ubiquitously expressed. To better understand the etiology of peroxisomal myelin diseases, we aimed to label these organelles in vivo and in a cell type specific fashion. We had previously shown that in oligodendrocytes and Schwann cells numerous peroxisomes reside in the cytoplasmic channels of "non-compacted" myelin. These organelles are smaller and biochemically distinct from non-myelin peroxisomes. Targeting peroxisomal functions in various cell types of the brain has demonstrated that oligodendroglial peroxisomes are specifically important for long-term integrity of the CNS. To visualize myelin peroxisomes in intact cells and tissues by live imaging, we have generated a novel line of transgenic mice for the expression of fluorescently tagged peroxisomes specifically in myelinating glia. This was achieved by modifying the gene for a photoconvertible mEos2 with a peroxisomal targeting signal type 1 (PTS1) and generating a fusion gene with the myelin-specific Cnp1 promoter. In the brain of resulting transgenic mice, peroxisomes are selectively labeled in oligodendrocytes. In this novel genetic tool, photoconversion of single peroxisomes from green to red fluorescence can be used to monitor the fate of single organelles and to determine the dynamics of PTS1-mediated protein import in the context of myelin diseases that affect peroxisomal functions. PMID:24262602

  4. Selective and antigen-dependent effects of myelin degeneration on central nervous system inflammation.

    PubMed

    Aboul-Enein, Fahmy; Bauer, Jan; Klein, Matthias; Schubart, Anna; Flügel, Alexander; Ritter, Thomas; Kawakami, Naoto; Siedler, Frank; Linington, Christopher; Wekerle, Hartmut; Lassmann, Hans; Bradl, Monika

    2004-12-01

    Damage to myelin sheath or oligodendrocytes may precede or even provoke inflammation of the central nervous system (CNS), but the extent to which these degenerative changes affect inflammation remains largely undefined. To study these processes in more detail, we used CNS antigen-specific T cells in the presence or absence of anti-myelin antibodies to induce experimental autoimmune encephalomyelitis (EAE) in transgenic Lewis rats with low-grade subclinical myelin degeneration and associated microglia cell activation, and in wild-type Lewis rats with an intact CNS. We found that myelin degeneration affects the localization of inflammatory lesions, the numbers of T cells recruited to these lesions, and the severity of the resulting clinical disease. In addition, myelin degeneration and associated microglia cell activation jointly enhance the susceptibility of the CNS to the action of anti-myelin antibodies. Our data show that even subtle alterations of myelin and oligodendrocytes may massively amplify the extent of demyelination and tissue damage, involving different immune effector mechanisms. A similar causal relationship might also operate in human patients with multiple sclerosis, where T cell-mediated inflammation and antibody-mediated demyelination have been documented, and where genetic factors might determine the susceptibility of the target tissue for immune-mediated injury. PMID:15624765

  5. Channeling of developing rat corticospinal tract axons by myelin-associated neurite growth inhibitors

    SciTech Connect

    Schwab, M.E.; Schnell, L. )

    1991-03-01

    CNS myelin contains 2 membrane proteins that are potent inhibitors of neurite growth (NI-35 and NI-250). Because myelin formation starts at different times in different regions and tracts of the CNS, this inhibitory property of myelin could serve boundary and guidance functions for late-growing fiber tracts. In the rat, the corticospinal tract (CST) grows into and down the spinal cord during the first 10 postnatal days, in close proximity to the sensory tracts fasciculus cuneatus and gracilis. Immunofluorescence for myelin constituents showed that, in the rostral half of the spinal cord, the myelinating tissue of these ascending tracts surrounds the growing, myelin-free CST in a channellike fashion. Elimination of oligodendrocytes by x-irradiation of the newborn rats, or application of antibody IN-1, which neutralizes the inhibitory substrate property of CNS myelin, resulted in significant anatomical aberration of CST fibers. In particular, the tract was larger in cross-section, and aberrant CST fibers and fascicles intermixed with the neighboring sensory ascending tracts. These results assign an important channeling and guard-rail function to the oligodendrocyte-associated neurite growth inhibitors for the developing CST in the rat spinal cord.

  6. Progesterone and nestorone promote myelin regeneration in chronic demyelinating lesions of corpus callosum and cerebral cortex.

    PubMed

    El-Etr, Martine; Rame, Marion; Boucher, Celine; Ghoumari, Abdel M; Kumar, Narender; Liere, Philippe; Pianos, Antoine; Schumacher, Michael; Sitruk-Ware, Regine

    2015-01-01

    Multiple Sclerosis affects mainly women and consists in intermittent or chronic damages to the myelin sheaths, focal inflammation, and axonal degeneration. Current therapies are limited to immunomodulators and antiinflammatory drugs, but there is no efficient treatment for stimulating the endogenous capacity of myelin repair. Progesterone and synthetic progestins have been shown in animal models of demyelination to attenuate myelin loss, reduce clinical symptoms severity, modulate inflammatory responses and partially reverse the age-dependent decline in remyelination. Moreover, progesterone has been demonstrated to promote myelin formation in organotypic cultures of cerebellar slices. In the present study, we show that progesterone and the synthetic 19-nor-progesterone derivative Nestorone® promote the repair of severe chronic demyelinating lesions induced by feeding cuprizone to female mice for up to 12 weeks. Progesterone and Nestorone increase the density of NG2(+) oligodendrocyte progenitor cells and CA II(+) mature oligodendrocytes and enhance the formation of myelin basic protein (MBP)- and proteolipid protein (PLP)-immunoreactive myelin. However, while demyelination in response to cuprizone was less marked in corpus callosum than in cerebral cortex, remyelination appeared earlier in the former. The remyelinating effect of progesterone was progesterone receptor (PR)-dependent, as it was absent in PR-knockout mice. Progesterone and Nestorone also decreased (but did not suppress) neuroinflammatory responses, specifically astrocyte and microglial cell activation. Therefore, some progestogens are promising therapeutic candidates for promoting the regeneration of myelin. PMID:25092805

  7. Erythropoietin promotes oligodendrogenesis and myelin repair following lysolecithin-induced injury in spinal cord slice culture

    SciTech Connect

    Cho, Yun Kyung; Kim, Gunha; Park, Serah; Sim, Ju Hee; Won, You Jin; Hwang, Chang Ho; Yoo, Jong Yoon; Hong, Hea Nam

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer Lysolecithin-induced demyelination elevated EpoR expression in OPCs. Black-Right-Pointing-Pointer In association with elevated EpoR, EPO increased OPCs proliferation. Black-Right-Pointing-Pointer EPO enhanced the oligodendrogenesis via activation of JAK2 pathway. Black-Right-Pointing-Pointer EPO promoted myelin repair following lysolecithin-induced demyelination. -- Abstract: Here, we sought to delineate the effect of EPO on the remyelination processes using an in vitro model of demyelination. We report that lysolecithin-induced demyelination elevated EPO receptor (EpoR) expression in oligodendrocyte progenitor cells (OPCs), facilitating the beneficial effect of EPO on the formation of oligodendrocytes (oligodendrogenesis). In the absence of EPO, the resultant remyelination was insufficient, possibly due to a limiting number of oligodendrocytes rather than their progenitors, which proliferate in response to lysolecithin-induced injury. By EPO treatment, lysolecithin-induced proliferation of OPCs was accelerated and the number of myelinating oligodendrocytes and myelin recovery was increased. EPO also enhanced the differentiation of neural progenitor cells expressing EpoR at high level toward the oligodendrocyte-lineage cells through activation of cyclin E and Janus kinase 2 pathways. Induction of myelin-forming oligodendrocytes by high dose of EPO implies that EPO might be the key factor influencing the final differentiation of OPCs. Taken together, our data suggest that EPO treatment could be an effective way to enhance remyelination by promoting oligodendrogenesis in association with elevated EpoR expression in spinal cord slice culture after lysolecithin-induced demyelination.

  8. Oligodendrocyte Responses to Buprenorphine Uncover Novel and Opposing Roles of μ-Opioid- and Nociceptin/Orphanin FQ Receptors in Cell Development: Implications for Drug Addiction Treatment During Pregnancy

    PubMed Central

    Eschenroeder, Andrew C.; Vestal-Laborde, Allison A.; Sanchez, Emilse S.; Robinson, Susan E.; Sato-Bigbee, Carmen

    2011-01-01

    While the classical function of myelin is the facilitation of saltatory conduction, this membrane and the oligodendrocytes, the cells that make myelin in the central nervous system (CNS), are now recognized as important regulators of plasticity and remodeling in the developing brain. As such, oligodendrocyte maturation and myelination are among the most vulnerable processes along CNS development. We have shown previously that rat brain myelination is significantly altered by buprenorphine, an opioid analogue currently used in clinical trials for managing pregnant opioid addicts. Perinatal exposure to low levels of this drug induced accelerated and increased expression of myelin basic proteins (MBPs), cellular and myelin components that are markers of mature oligodendrocytes. In contrast, supra-therapeutic drug doses delayed MBP brain expression and resulted in a decreased number of myelinated axons. We have now found that this biphasic-dose response to buprenorphine can be attributed to the participation of both the μ-opioid receptor (MOR) and the nociceptin/orphanin FQ receptor (NOP receptor) in the oligodendrocytes. This is particularly intriguing because the NOP receptor/nociceptin system has been primarily linked to behavior and pain regulation, but a role in CNS development or myelination has not been described before. Our findings suggest that balance between signaling mediated by (a) MOR activation and (b) a novel, yet unidentified pathway that includes the NOP receptor, plays a crucial role in the timing of oligodendrocyte maturation and myelin synthesis. Moreover, exposure to opioids could disrupt the normal interplay between these two systems altering the developmental pattern of brain myelination. PMID:22002899

  9. Oligodendrocyte responses to buprenorphine uncover novel and opposing roles of μ-opioid- and nociceptin/orphanin FQ receptors in cell development: implications for drug addiction treatment during pregnancy.

    PubMed

    Eschenroeder, Andrew C; Vestal-Laborde, Allison A; Sanchez, Emilse S; Robinson, Susan E; Sato-Bigbee, Carmen

    2012-01-01

    Although the classical function of myelin is the facilitation of saltatory conduction, this membrane and the oligodendrocytes, the cells that make myelin in the central nervous system (CNS), are now recognized as important regulators of plasticity and remodeling in the developing brain. As such, oligodendrocyte maturation and myelination are among the most vulnerable processes along CNS development. We have shown previously that rat brain myelination is significantly altered by buprenorphine, an opioid analogue currently used in clinical trials for managing pregnant opioid addicts. Perinatal exposure to low levels of this drug induced accelerated and increased expression of myelin basic proteins (MBPs), cellular and myelin components that are markers of mature oligodendrocytes. In contrast, supra-therapeutic drug doses delayed MBP brain expression and resulted in a decreased number of myelinated axons. We have now found that this biphasic-dose response to buprenorphine can be attributed to the participation of both the μ-opioid receptor (MOR) and the nociceptin/orphanin FQ receptor (NOP receptor) in the oligodendrocytes. This is particularly intriguing because the NOP receptor/nociceptin system has been primarily linked to behavior and pain regulation, but a role in CNS development or myelination has not been described before. Our findings suggest that balance between signaling mediated by (a) MOR activation and (b) a novel, yet unidentified pathway that includes the NOP receptor, plays a crucial role in the timing of oligodendrocyte maturation and myelin synthesis. Moreover, exposure to opioids could disrupt the normal interplay between these two systems altering the developmental pattern of brain myelination. PMID:22002899

  10. Completion of myelin compaction, but not the attachment of oligodendroglial processes triggers K(+) channel clustering.

    PubMed

    Baba, H; Akita, H; Ishibashi, T; Inoue, Y; Nakahira, K; Ikenaka, K

    1999-12-15

    The characteristic localization of ion channels is crucial for the propagation of saltatory conduction in myelinated nerves. Voltage-gated Na(+) channels are located at nodes of Ranvier while voltage-gated K(+) channels are mainly found at juxtaparanodal regions. Recently, a humoral factor secreted by oligodendrocytes has been reported to induce clustering of Na(+) channels in CNS axons. However, the molecular mechanisms for K(+) channel clustering as well as the role of oligodendrocytes are still uncertain. To clarify whether myelin sheath itself can induce the distinct distribution of K(+) channels, we have investigated the localization of K(+) channels in adult and developing mouse optic nerves. The CNS axons from chronic demyelinating and hypomyelinating mice were also examined to determine if myelin sheaths were required for the maintenance of clusters. In all cases, the K(+) channel clustering correlated well with compact myelin, but not with the presence of oligodendrocytes, suggesting that, in contrast to Na(+) channel clustering, the formation of compact myelin is required for initiation as well as maintenance of K(+) channel clustering. In addition, postsynaptic density protein-95 (PSD-95) or its highly related protein was found colocalized with K(+) channels, suggesting that it may interact with K(+) channels to form clusters at juxtaparanodal regions. PMID:10583907

  11. Perinatal chronic hypoxia induces cortical inflammation, hypomyelination, and peripheral myelin-specific T cell autoreactivity.

    PubMed

    Ortega, Sterling B; Kong, Xiagmei; Venkataraman, Ramgopal; Savedra, Allen Michael; Kernie, Steven G; Stowe, Ann M; Raman, Lakshmi

    2016-01-01

    pCH is an important risk factor for brain injury and long-term morbidity in children, occurring during the developmental stages of neurogenesis, neuronal migration, and myelination. We show that a rodent model of pCH results in an early decrease in mature myelin. Although pCH does increase progenitor oligodendrocytes in the developing brain, BrdU labeling revealed a loss in dividing progenitor oligodendrocytes, indicating a defect in mature cell replacement and myelinogenesis. Mice continued to exhibited hypomyelination, concomitant with long-term impairment of motor function, weeks after cessation of pCH. The implication of a novel neuroimmunologic interplay, pCH also induced a significant egress of infiltrating CD4 T cells into the developing brain. This pCH-mediated neuroinflammation included oligodendrocyte-directed autoimmunity, with an increase in peripheral myelin-specific CD4 T cells. Thus, both the loss of available, mature, myelin-producing glial cells and an active increase in autoreactive, myelin-specific CD4 T cell infiltration into pCH brains may contribute to early pCH-induced hypomyelination in the developing CNS. The elucidation of potential mechanisms of hypoxia-driven autoimmunity will expand our understanding of the neuroimmune axis during perinatal CNS disease states that may contribute to long-term functional disability. PMID:26038434

  12. Tamoxifen promotes differentiation of oligodendrocyte progenitors in vitro.

    PubMed

    Barratt, H E; Budnick, H C; Parra, R; Lolley, R J; Perry, C N; Nesic, O

    2016-04-01

    The most promising therapeutic approach to finding the cure for devastating demyelinating conditions is the identification of clinically safe pharmacological agents that can promote differentiation of endogenous oligodendrocyte precursor cells (OPCs). Here we show that the breast cancer medication tamoxifen (TMX), with well-documented clinical safety and confirmed beneficial effects in various models of demyelinating conditions, stimulates differentiation of rat glial progenitors to mature oligodendrocytes in vitro. Clinically applicable doses of TMX significantly increased both the number of CNPase-positive oligodendrocytes and protein levels of myelin basic protein, measured with Western blots. Furthermore, we also found that OPC differentiation was stimulated, not only by the pro-drug TMX-citrate (TMXC), but also by two main TMX metabolites, 4-hydroxy-TMX and endoxifen. Differentiating effects of TMXC and its metabolites were completely abolished in the presence of estrogen receptor (ER) antagonist, ICI182780. In contrast to TMXC and 4-hydroxy-TMX, endoxifen also induced astrogliogenesis, but independent of the ER activation. In sum, we showed that the TMX prodrug and its two main metabolites (4-hydroxy-TMX and endoxifen) promote ER-dependent oligodendrogenesis in vitro, not reported before. Given that differentiating effects of TMX were achieved with clinically safe doses, TMX is likely one of the most promising FDA-approved drugs for the possible treatment of demyelinating diseases. PMID:26820594

  13. MYRF is a membrane-associated transcription factor that autoproteolytically cleaves to directly activate myelin genes.

    PubMed

    Bujalka, Helena; Koenning, Matthias; Jackson, Stacey; Perreau, Victoria M; Pope, Bernard; Hay, Curtis M; Mitew, Stanlislaw; Hill, Andrew F; Lu, Q Richard; Wegner, Michael; Srinivasan, Rajini; Svaren, John; Willingham, Melanie; Barres, Ben A; Emery, Ben

    2013-01-01

    The myelination of axons is a crucial step during vertebrate central nervous system (CNS) development, allowing for rapid and energy efficient saltatory conduction of nerve impulses. Accordingly, the differentiation of oligodendrocytes, the myelinating cells of the CNS, and their expression of myelin genes are under tight transcriptional control. We previously identified a putative transcription factor, Myelin Regulatory Factor (Myrf), as being vital for CNS myelination. Myrf is required for the generation of CNS myelination during development and also for its maintenance in the adult. It has been controversial, however, whether Myrf directly regulates transcription, with reports of a transmembrane domain and lack of nuclear localization. Here we show that Myrf is a membrane-associated transcription factor that undergoes an activating proteolytic cleavage to separate its transmembrane domain-containing C-terminal region from a nuclear-targeted N-terminal region. Unexpectedly, this cleavage event occurs via a protein domain related to the autoproteolytic intramolecular chaperone domain of the bacteriophage tail spike proteins, the first time this domain has been found to play a role in eukaryotic proteins. Using ChIP-Seq we show that the N-terminal cleavage product directly binds the enhancer regions of oligodendrocyte-specific and myelin genes. This binding occurs via a defined DNA-binding consensus sequence and strongly promotes the expression of target genes. These findings identify Myrf as a novel example of a membrane-associated transcription factor and provide a direct molecular mechanism for its regulation of oligodendrocyte differentiation and CNS myelination. PMID:23966833

  14. Insulin influenced expression of myelin proteins in diabetic peripheral neuropathy.

    PubMed

    Rachana, Kuruvanthe S; Manu, Mallahalli S; Advirao, Gopal M

    2016-08-26

    Diabetic peripheral neuropathy (DPN) is one of the downstream complications of diabetes. This complication is caused by the deficiency of insulin action and subsequent hyperglycemia, but the details of their pathogenesis remain unclear. Hence, it is of critical importance to understand how such hormonal variation affects the expression of myelin proteins such as myelin basic protein (MBP) and myelin associated glycoprotein (MAG) in the peripheral nerve. An earlier report from our lab has demonstrated the expression of insulin receptors (IR) in Schwann cells (SCs) of sciatic nerve. To assess the neurotrophic role of insulin in diabetic neuropathy, we studied the expression of these myelin proteins under control, DPN and insulin treated DPN subjects at developmental stages. Further, the expression of these myelin proteins was correlated with the expression of insulin receptor. Expression of myelin proteins was significantly reduced in the diabetic model compared to normal, and upregulated in insulin treated diabetic rats. Similarly, an in vitro study was also carried out in SCs grown at high glucose and insulin treated conditions. The expression pattern of myelin proteins in SCs was comparable to that of in vivo samples. In addition, quantitative study of myelin genes by real time PCR has also showed the significant expression pattern change in the insulin treated and non-treated DPN subjects. Taken together, these results corroborate the critical importance of insulin as a neurotrophic factor in demyelinized neurons in diabetic neuropathy. PMID:27373589

  15. Chronic Expression of PPAR-δ by Oligodendrocyte Lineage Cells in the Injured Rat Spinal Cord

    PubMed Central

    Almad, Akshata; McTigue, Dana M.

    2014-01-01

    The transcription factor peroxisome proliferator-activated receptor (PPAR)-δ promotes oligodendrocyte differentiation and myelin formation in vitro and is prevalent throughout the brain and spinal cord. Its expression after injury, however, has not been examined. Thus, we used a spinal contusion model to examine the spatiotemporal expression of PPAR-δ in naïve and injured spinal cords from adult rats. As previously reported, PPAR-δ was expressed by neurons and oligodendrocytes in uninjured spinal cords; PPAR-δ was also detected in NG2 cells (potential oligodendrocyte progenitors) within the white matter and gray matter. After spinal cord injury (SCI), PPAR-δ mRNA and protein were present early and increased over time. Overall PPAR-δ+ cell numbers declined at 1 day post injury (dpi), likely reflecting neuron loss, and then rose through 14 dpi. A large proportion of NG2 cells expressed PPAR-δ after SCI, especially along lesion borders. PPAR-δ+ NG2 cell numbers were significantly higher than naive by 7 dpi and remained elevated through at least 28 dpi. PPAR-δ+ oligodendrocyte numbers declined at 1 dpi and then increased over time such that >20% of oligodendrocytes expressed PPAR-δ after SCI compared with ~10% in uninjured tissue. The most prominent increase in PPAR-δ+ oligodendrocytes was along lesion borders where at least a portion of newly generated oligodendrocytes (bromode-oxyuridine +) were PPAR-δ+. Consistent with its role in cellular differentiation, the early rise in PPAR-δ+ NG2 cells followed by an increase in new PPAR-δ+ oligodendrocytes suggests that this transcription factor may be involved in the robust oligodendrogenesis detected previously along SCI lesion borders. PMID:20058304

  16. Characterization of cultured rat oligodendrocytes proliferating in a serum-free, chemically defined medium

    SciTech Connect

    Saneto, R.P.; de Vellis, J.

    1985-05-01

    A serumless, chemically defined medium has been developed for the culture of oligodendrocytes isolated from primary neonatal rat cerebral cultures. Combined together, insulin, transferrin, and fibroblast growth factor synergistically induced an essentially homogeneous population (95-98%) of cells expressing glycerol-3-phosphate dehydrogenase activity to undergo cell division. Proliferating cells were characterized by several criteria: (i) ultrastructural analysis by transmission electron microscopy identified the cell type as an oligodendrocyte; (ii) biochemical assays showed expression of three oligodendrocyte biochemical markers, induction of both glycerol phosphate dehydrogenase and lactate dehydrogenase, and presence of 2',3'-cyclic nucleotide 3'-phosphodiesterase; and (iii) immunocytochemical staining showed cultures to be 95-98% positive for glycerol phosphate dehydrogenase, 90% for myelin basic protein, 60-70% for galactocerebroside, and 70% for A2B5.

  17. Schwann Cell Myelination Requires Timely and Precise Targeting of P0 Protein

    PubMed Central

    Yin, X.; Kidd, G.J.; Wrabetz, L.; Feltri, M.L.; Messing, A.; Trapp, B.D.

    2000-01-01

    This report investigated mechanisms responsible for failed Schwann cell myelination in mice that overexpress P0 (P0tg), the major structural protein of PNS myelin. Quantitative ultrastructural immunocytochemistry established that P0 protein was mistargeted to abaxonal, periaxonal, and mesaxon membranes in P0tg Schwann cells with arrested myelination. The extracellular leaflets of P0-containing mesaxon membranes were closely apposed with periodicities of compact myelin. The myelin-associated glycoprotein was appropriately sorted in the Golgi apparatus and targeted to periaxonal membranes. In adult mice, occasional Schwann cells myelinated axons possibly with the aid of endocytic removal of mistargeted P0. These results indicate that P0 gene multiplication causes P0 mistargeting to mesaxon membranes, and through obligate P0 homophilic adhesion, renders these dynamic membranes inert and halts myelination. PMID:10704450

  18. Interaction of mTOR and Erk1/2 signaling to regulate oligodendrocyte differentiation.

    PubMed

    Dai, JinXiang; Bercury, Kathryn K; Macklin, Wendy B

    2014-12-01

    A multitude of factors regulate oligodendrocyte differentiation and remyelination, and to elucidate the mechanisms underlying this process, we analyzed the interactions of known signaling pathways involved in these processes. Previous work from our lab and others shows that Akt, mTOR, and Erk 1/2 are major signaling pathways regulating oligodendrocyte differentiation and myelination in vitro and in vivo. However, the relative contribution of the different pathways has been difficult to establish because the impact of inhibiting one pathway in in vitro cell culture models or in vivo may alter signaling through the other pathway. These studies were undertaken to clarify the interactions between these major pathways and understand more specifically the crosstalk between them. Oligodendrocyte differentiation in vitro required Akt, mTOR, and Erk 1/2 signaling, as inhibition of Akt, mTOR, or Erk 1/2 resulted in a significant decrease of myelin basic protein mRNA and protein expression. Interestingly, while inhibition of the Erk1/2 pathway had little impact on Akt/mTOR signaling, inhibition of the Akt/mTOR pathways significantly increased Erk1/2 signaling, although not enough to overcome the loss of Akt/mTOR signaling in the regulation of oligodendrocyte differentiation. Furthermore, such crosstalk was also noted in an in vivo context, after mTOR inhibition by rapamycin treatment of perinatal pups. GLIA 2014;62:2096-2109. PMID:25060812

  19. Oligodendrocyte Lineage Cells in Chronic Demyelination of Multiple Sclerosis Optic Nerve.

    PubMed

    Jennings, Alison Ruth; Carroll, William M

    2015-09-01

    Reports that chronically demyelinated multiple sclerosis brain and spinal cord lesions contained immature oligodendrocyte lineage cells have generated major interest aimed at the potential for promotion of endogenous repair. Despite the prominence of the optic nerve as a lesion site and its importance in clinical disease assessment, no detailed studies of multiple sclerosis-affected optic nerve exist. This study aims to provide insight into the cellular pathology of chronic demyelination in multiple sclerosis through direct morphological and immunohistochemical analysis of optic nerve in conjunction with observations from an experimental cat optic nerve model of successful remyelination. Myelin staining was followed by immunohistochemistry to differentially label neuroglia. Digitally immortalized sections were then analyzed to generate quantification data and antigenic phenotypes including maturational stages within the oligodendrocyte lineage. It was found that some chronically demyelinated multiple sclerosis optic nerve lesions contained oligodendroglial cells and that heterogeneity existed in the presence of myelin sheaths, oligodendrocyte maturational stages and extent of axonal investment. The findings advance our understanding of oligodendrocyte activity in chronically demyelinated human optic nerve and may have implications for studies aimed at enhancement of endogenous repair in multiple sclerosis. PMID:25175564

  20. Aorta-derived mesoangioblasts differentiate into the oligodendrocytes by inhibition of the Rho kinase signaling pathway.

    PubMed

    Wang, Lei; Kamath, Anant; Frye, Janie; Iwamoto, Gary A; Chun, Ju Lan; Berry, Suzanne E

    2012-05-01

    Mesoangioblasts are vessel-derived stem cells that differentiate into mesodermal derivatives. We have isolated postnatal aorta-derived mesoangioblasts (ADMs) that differentiate into smooth, skeletal, and cardiac muscle, and adipocytes, and regenerate damaged skeletal muscle in a murine model for Duchenne muscular dystrophy. We report that the marker profile of ADM is similar to that of mesoangioblasts isolated from embryonic dorsal aorta, postnatal bone marrow, and heart, but distinct from mesoangioblasts derived from skeletal muscle. We also demonstrate that ADM differentiate into myelinating glial cells. ADM localize to peripheral nerve bundles in regenerating muscles and exhibit morphology and marker expression of mature Schwann cells, and myelinate axons. In vitro, ADM spontaneously express markers of oligodendrocyte progenitors, including the chondroitin sulphate proteoglycan NG2, nestin, platelet-derived growth factor (PDGF) receptor α, the A2B5 antigen, thyroid hormone nuclear receptor α, and O4. Pharmacological inhibition of Rho kinase (ROCK) initiated process extension by ADM, and when combined with insulin-like growth factor 1, PDGF, and thyroid hormone, enhanced ADM expression of oligodendrocyte precursor markers and maturation into the oligodendrocyte lineage. ADM injected into the right lateral ventricle of the brain migrate to the corpus callosum, and cerebellar white matter, where they express components of myelin. Because ADM differentiate or mature into cell types of both mesodermal and ectodermal origin, they may be useful for treatment of a variety of degenerative diseases, or repair and regeneration of multiple cell types in severely damaged tissue. PMID:21793703

  1. p38 Mitogen-Activated Protein Kinase Pathway Regulates Genes during Proliferation and Differentiation in Oligodendrocytes

    PubMed Central

    Haines, Jeffery D.; Fulton, Debra L.; Richard, Stephane; Almazan, Guillermina

    2015-01-01

    We have previously shown that p38 mitogen-activated protein kinase (p38 MAPK) is important for oligodendrocyte (OLG) differentiation and myelination. However, the precise cellular mechanisms by which p38 regulates OLG differentiation remain largely unknown. To determine whether p38 functions in part through transcriptional events in regulating OLG identity, we performed microarray analysis on differentiating oligodendrocyte progenitors (OLPs) treated with a p38 inhibitor. Consistent with a role in OLG differentiation, pharmacological inhibition of p38 down-regulated the transcription of genes that are involved in myelin biogenesis, transcriptional control and cell cycle. Proliferation assays showed that OLPs treated with the p38 inhibitor retained a proliferative capacity which could be induced upon application of mitogens demonstrating that after two days of p38-inhibition OLGs remained poised to continue mitosis. Together, our results suggest that the p38 pathway regulates gene transcription which can coordinate OLG differentiation. Our microarray dataset will provide a useful resource for future studies investigating the molecular mechanisms by which p38 regulates oligodendrocyte differentiation and myelination. PMID:26714323

  2. Effects of experimental hypothyroidism on myelin sheath structural organization.

    PubMed

    Ferreira, Andréa A; Nazário, José C; Pereira, Mário J S; Azevedo, Neide L; Barradas, Penha C

    2004-03-01

    A previous study using the 2'3'cyclic nucleotide 3'phosphodiesterase (CNPase), an oligodendroglial marker that also stain ensheathed fibers, showed a decrease in the number of immunoreactive fibers and a change in the pattern of CNPase immunoreactivity (CNPase+) in hypothyroid animals. CNPase+ fibers, in mature hypothyroid animals, showed a continuous pattern of staining in contrast with a discontinuous one in controls. As CNPase, in adult animals, can be found only in regions in which oligodendrocyte cytoplasm remains as internal, external and paranodal loops, it was suggested that the reduction of thyroid hormone levels leads to a failure in myelin compaction. Previous data showed a higher frequency of some abnormalities in myelin sheath as multiple cytoplasmic loops and redundant myelin profiles in mutant animals that present a failure in myelin compaction. The increase in the frequency of these abnormalities (multiple internal and external loops and redundant myelin) indicates a failure in the interrelations between the axons and the oligodendroglial processes. To verify if the thyroid hormone deficiency during CNS development disturbs these interrelations, we evaluated the frequency of the morphological abnormalities (multiple internal and external loops and redundant myelin) in myelin sheath of corpus callosum (cc) in experimental hypothyroidism. Randomic fields were kept by electron microscopy and the analysis of the frequency of morphological abnormalities showed a significant difference in hypothyroid animals at 60-day-old (PND60), with no significant differences at 90-day-old (PND90) animals. The frequency of multiple internal loops is higher in hypothyroid animals at PND60 that indicates a disturbance in the wrapping by the oligodendroglial process. These findings showed that thyroid hormone might modulate the axon-oligodendroglial relationships that are important for the adequate temporal sequence of events that occur during myelinogenesis, with

  3. Galectin-4, a novel neuronal regulator of myelination.

    PubMed

    Stancic, Mirjana; Slijepcevic, Davor; Nomden, Anita; Vos, Michel J; de Jonge, Jenny C; Sikkema, Arend H; Gabius, Hans-J; Hoekstra, Dick; Baron, Wia

    2012-05-01

    Myelination of axons by oligodendrocytes (OLGs) is essential for proper saltatory nerve conduction, i.e., rapid transmission of nerve impulses. Among others, extracellular matrix (ECM) molecules, neuronal signaling, and axonal adhesion regulate the biogenesis and maintenance of myelin membranes, driven by polarized transport of myelin-specific proteins and lipids. Galectin-4, a tandem-repeat-type lectin with affinity to sulfatide and nonsialylated termini of N-glycans, has the ability to regulate adhesion of cells to ECM components and is also involved in polarized membrane trafficking. We, therefore, anticipated that galectin-4 might play a role in myelination. Here, we show that in developing postnatal rat brains galectin-4 expression is downregulated just before the onset of myelination. Intriguingly, when immature OLGs were treated with galectin-4, OLG maturation was retarded, while a subset of the immature OLGs reverted to a morphologically less complex progenitor stage, displaying concomitantly an increase in proliferation. Similarly, myelination was inhibited when galectin-4 or anti-galectin-4 antibodies were added to co-cultures of dorsal root ganglion neurons and OLGs. Neurons and OLGs were identified as a possible source of galectin-4, both in vitro and in vivo. In culture, neurons but not OLGs released galectin-4. Interestingly, in co-cultures, a reduced release of endogenous galectin-4 correlated with the onset of myelination. Moreover, galectin-4-reactive sites are transiently expressed on processes of premyelinating primary OLGs, but not on neurons. Taken together, these results identify neuronal galectin-4 as a candidate for a soluble regulator of OLG differentiation and, hence, myelination. © 2012 Wiley Periodicals, Inc. PMID:22431161

  4. Myelin Avoids the JAM.

    PubMed

    Follis, Rose M; Carter, Bruce D

    2016-08-17

    In this issue of Neuron, Redmond et al. (2016) identify junction adhesion molecule 2 (JAM2) as an inhibitor of somatodendritic myelination in spinal cord neurons, thereby elucidating how myelin forms on axons but avoids dendrites and cell bodies. PMID:27537479

  5. A genetic screen identifies genes essential for development of myelinated axons in zebrafish.

    PubMed

    Pogoda, Hans-Martin; Sternheim, Nitzan; Lyons, David A; Diamond, Brianne; Hawkins, Thomas A; Woods, Ian G; Bhatt, Dimple H; Franzini-Armstrong, Clara; Dominguez, Claudia; Arana, Naomi; Jacobs, Jennifer; Nix, Rebecca; Fetcho, Joseph R; Talbot, William S

    2006-10-01

    The myelin sheath insulates axons in the vertebrate nervous system, allowing rapid propagation of action potentials via saltatory conduction. Specialized glial cells, termed Schwann cells in the PNS and oligodendrocytes in the CNS, wrap axons to form myelin, a compacted, multilayered sheath comprising specific proteins and lipids. Disruption of myelinated axons causes human diseases, including multiple sclerosis and Charcot-Marie-Tooth peripheral neuropathies. Despite the progress in identifying human disease genes and other mutations disrupting glial development and myelination, many important unanswered questions remain about the mechanisms that coordinate the development of myelinated axons. To address these questions, we began a genetic dissection of myelination in zebrafish. Here we report a genetic screen that identified 13 mutations, which define 10 genes, disrupting the development of myelinated axons. We present the initial characterization of seven of these mutations, defining six different genes, along with additional characterization of mutations that we have described previously. The different mutations affect the PNS, the CNS, or both, and phenotypic analyses indicate that the genes affect a wide range of steps in glial development, from fate specification through terminal differentiation. The analysis of these mutations will advance our understanding of myelination, and the mutants will serve as models of human diseases of myelin. PMID:16875686

  6. Theory of myelin coiling.

    PubMed

    Huang, J-R

    2006-04-01

    A new model is proposed to explain coiling of myelins composed of fluid bilayers. This model allows the constituent bilayer cylinders of a myelin to be non-coaxial and the bilayer lateral tension to vary from bilayer to bilayer. The calculations show that a myelin would bend or coil to lower its free energy when the bilayer lateral tension is sufficiently large. From a mechanical point of view, the proposed coiling mechanism is analogous to the classical Euler buckling of a thin elastic rod under axial compression. The analysis of a simple two-bilayer case suggests that a bilayer lateral tension of about 1 dyne/cm can easily induce coiling of myelins of typical lipid bilayers. This model signifies the importance of bilayer lateral tension in determining the morphology of myelinic structures. PMID:16465468

  7. Composition and biophysical properties of myelin lipid define the neurological defects in galactocerebroside- and sulfatide-deficient mice.

    PubMed

    Bosio, A; Binczek, E; Haupt, W F; Stoffel, W

    1998-01-01

    Oligodendrocytes and Schwann cell-specific proteins are assembled with a highly ordered membrane lipid bilayer to the myelin sheath of axons, which functions as an insulator and allows rapid saltatory conduction. We approached the question of the function of the CNS and PNS myelin-specific galactospingolipids cerebrosides and sulfatides by generating a ceramide galactosyltransferase null allelic mouse line (cgt-/-). Galactocerebroside- and sulfatide-deficient myelin loses its insulating properties and causes a severe dysmyelinosis that is incompatible with life. Here, we describe the biochemical and biophysical analysis of the myelin lipid bilayer of cgt-/- mice. The lipid composition of CNS and PNS myelin of cgt-/- mice is seriously perturbed and the sphingolipid biosynthetic pathway altered. Nonhydroxy and hydroxy fatty acid-substituted glycosylceramides (GlcC) are synthesized by oligodendrocytes and sulfated GlcC in addition in Schwann cells. The monogalactosyldiglyceride fraction is missing in the cgt-/- mouse. This new lipid composition can be correlated with the biophysical properties of the myelin sheath. The deficiency of galactocerebrosides and sulfatides leads to an increased fluidity, permeability, and impaired packing of the myelin lipid bilayer of the internodal membrane system. The loss of the two glycosphingolipid classes causes the breakdown of saltatory conductance of myelinated axons in the cgt-/- mouse. PMID:9422376

  8. Early IFN-γ production together with decreased expression of TLR3 and TLR9 characterizes EAE development conditional on the presence of myelin.

    PubMed

    Evangelista, Marcilene Gomes; Castro, Sandra Bertelli Ribeiro De; Alves, Caio César De Souza; Dias, Alyria Teixeira; Souza, Viano Wyallison De; Reis, Lívia Bittencourt Dos; Silva, Luan Cristian Da; Castañon, Maria Christina Marques Nogueira; Farias, Rogério Estevam; Juliano, Maria Aparecida; Ferreira, Ana Paula

    2016-06-01

    Experimental autoimmune encephalomyelitis (EAE) is a model for the study of multiple sclerosis, which is an inflammatory and demyelinating disease of the central nervous system (CNS). Despite increased efforts to elucidate the function of toll-like receptors (TLRs) in autoimmune diseases of the CNS, the relative contribution of other factors, including the immunomodulatory properties of TLR signaling, role of the innate response and the presence or absence of myelin peptides remain unclear. The aim was to evaluate TLR expression in the CNS during EAE development by investigating the expression of TLRs in the initial phase of EAE and establishing correlations with the modulation of inflammatory factors. Mice were subcutaneously immunized at the tail base with 100 μg of myelin oligodendrocyte glycoprotein peptide (MOG35-55), emulsified in complete Freund's adjuvant (CFA) supplemented with 400 μg of attenuated Mycobacterium tuberculosis H37RA. Pertussis toxin (300 ng per animal) was intraperitoneally injected on the day of immunization and 48 h later. Another group (MOG(-)) received an equal emulsion of CFA and M. tuberculosis, without MOG35-55, and the same protocol of Pertussis toxin. The immunized mice presented signs of disease with increased IFN-γ production and presence of NK cells on Day 2 postimmunization and reduced the expression of TLR-3 and TLR-9. In the spinal cord, CCL5 and CCL20 were higher in EAE. This study establishes a correlation between TLR-3 and TLR-9 expression with the development of EAE. In addition, evidence of a role for the myelin peptide in targeting the innate inflammatory response to the CNS is presented. PMID:26911613

  9. After Intracerebral Hemorrhage, Oligodendrocyte Precursors Proliferate and Differentiate Inside White-Matter Tracts in the Rat Striatum.

    PubMed

    Joseph, Michael J E; Caliaperumal, Jayalakshmi; Schlichter, Lyanne C

    2016-06-01

    Damage to myelinated axons contributes to neurological deficits after acute CNS injury, including ischemic and hemorrhagic stroke. Potential treatments to promote re-myelination will require fully differentiated oligodendrocytes, but almost nothing is known about their fate following intracerebral hemorrhage (ICH). Using a rat model of ICH in the striatum, we quantified survival, proliferation, and differentiation of oligodendrocyte precursor cells (OPCs) (at 1, 3, 7, 14, and 28 days) in the peri-hematoma region, surrounding striatum, and contralateral striatum. In the peri-hematoma, the density of Olig2(+) cells increased dramatically over the first 7 days, and this coincided with disorganization and fragmentation of myelinated axon bundles. Very little proliferation (Ki67(+)) of Olig2(+) cells was seen in the anterior subventricular zone from 1 to 28 days. However, by 3 days, many were proliferating in the peri-hematoma region, suggesting that local proliferation expands their population. By 14 days, the density of Olig2(+) cells declined in the peri-hematoma region, and, by 28 days, it reached the low level seen in the contralateral striatum. At these later times, many surviving axons were aligned into white-matter bundles, which appeared less swollen or fragmented. Oligodendrocyte cell maturation was prevalent over the 28-day period. Densities of immature OPCs (NG2(+)Olig2(+)) and mature (CC-1(+)Olig2(+)) oligodendrocytes in the peri-hematoma increased dramatically over the first week. Regardless of the maturation state, they increased preferentially inside the white-matter bundles. These results provide evidence that endogenous oligodendrocyte precursors proliferate and differentiate in the peri-hematoma region and have the potential to re-myelinate axon tracts after hemorrhagic stroke. PMID:26743212

  10. Modulation of oligodendrocyte differentiation and maturation by combined biochemical and mechanical cues

    PubMed Central

    Lourenço, Tânia; Paes de Faria, Joana; Bippes, Christian A.; Maia, João; Lopes-da-Silva, José A.; Relvas, João B.; Grãos, Mário

    2016-01-01

    Extracellular matrix (ECM) proteins play a key role during oligodendrogenesis. While fibronectin (FN) is involved in the maintenance and proliferation of oligodendrocyte progenitor cells (OPCs), merosin (MN) promotes differentiation into oligodendrocytes (OLs). Mechanical properties of the ECM also seem to affect OL differentiation, hence this study aimed to clarify the impact of combined biophysical and biochemical elements during oligodendrocyte differentiation and maturation using synthetic elastic polymeric ECM-like substrates. CG-4 cells presented OPC- or OL-like morphology in response to brain-compliant substrates functionalised with FN or MN, respectively. The expression of the differentiation and maturation markers myelin basic protein — MBP — and proteolipid protein — PLP — (respectively) by primary rat oligodendrocytes was enhanced in presence of MN, but only on brain-compliant conditions, considering the distribution (MBP) or amount (PLP) of the protein. It was also observed that maturation of OLs was attained earlier (by assessing PLP expression) by cells differentiated on MN-functionalised brain-compliant substrates than on standard culture conditions. Moreover, the combination of MN and substrate compliance enhanced the maturation and morphological complexity of OLs. Considering the distinct degrees of stiffness tested ranging within those of the central nervous system, our results indicate that 6.5 kPa is the most suitable rigidity for oligodendrocyte differentiation. PMID:26879561

  11. 17 β-estradiol Protects Male Mice from Cuprizone-induced Demyelination and Oligodendrocyte Loss

    PubMed Central

    Taylor, Lorelei C; Puranam, Kasturi; Gilmore, Wendy; Ting, Jenny P-Y.; Matsushima, G.K.

    2010-01-01

    In addition to regulating reproductive functions in the brain and periphery, estrogen has trophic and neuroprotective functions in the central nervous system (CNS). Estrogen administration has been demonstrated to provide protection in several animal models of CNS disorders, including stroke, brain injury, epilepsy, Parkinson’s disease, Alzheimer’s disease, age-related cognitive decline and multiple sclerosis. Here, we use a model of toxin-induced oligodendrocyte death which results in demyelination, reactive gliosis, recruitment of oligodendrocyte precursor cells and subsequent remyelination to study the potential benefit of 17β-estradiol (E2) administration in male mice. The results indicate that E2 partially ameliorates loss of oligodendrocytes and demyelination in the corpus callosum. This protection is accompanied by a delay in microglia accumulation as well as reduced mRNA expression of the pro-inflammatory cytokine, tumor necrosis factor alpha (TNFα), and insulin-like growth factor-1 (IGF-1). E2 did not significantly alter the accumulation of astrocytes or oligodendrocyte precursor cells, or remyelination. These data obtained from a toxin-induced, T cell-independent model using male mice provide an expanded view of the beneficial effects of estrogen on oligodendrocyte and myelin preservation. PMID:20347981

  12. Myelin-reactive antibodies initiate T cell-mediated CNS autoimmune disease by opsonization of endogenous antigen.

    PubMed

    Kinzel, Silke; Lehmann-Horn, Klaus; Torke, Sebastian; Häusler, Darius; Winkler, Anne; Stadelmann, Christine; Payne, Natalie; Feldmann, Linda; Saiz, Albert; Reindl, Markus; Lalive, Patrice H; Bernard, Claude C; Brück, Wolfgang; Weber, Martin S

    2016-07-01

    In the pathogenesis of central nervous system (CNS) demyelinating disorders, antigen-specific B cells are implicated to act as potent antigen-presenting cells (APC), eliciting waves of inflammatory CNS infiltration. Here, we provide the first evidence that CNS-reactive antibodies (Ab) are similarly capable of initiating an encephalitogenic immune response by targeting endogenous CNS antigen to otherwise inert myeloid APC. In a transgenic mouse model, constitutive production of Ab against myelin oligodendrocyte glycoprotein (MOG) was sufficient to promote spontaneous experimental autoimmune encephalomyelitis (EAE) in the absence of B cells, when mice endogenously contained MOG-recognizing T cells. Adoptive transfer studies corroborated that anti-MOG Ab triggered activation and expansion of peripheral MOG-specific T cells in an Fc-dependent manner, subsequently causing EAE. To evaluate the underlying mechanism, anti-MOG Ab were added to a co-culture of myeloid APC and MOG-specific T cells. At otherwise undetected concentrations, anti-MOG Ab enabled Fc-mediated APC recognition of intact MOG; internalized, processed and presented MOG activated naïve T cells to differentiate in an encephalitogenic manner. In a series of translational experiments, anti-MOG Ab from two patients with an acute flare of CNS inflammation likewise facilitated detection of human MOG. Jointly, these observations highlight Ab-mediated opsonization of endogenous CNS auto-antigen as a novel disease- and/or relapse-triggering mechanism in CNS demyelinating disorders. PMID:27022743

  13. MicroRNA-23a promotes myelination in the central nervous system.

    PubMed

    Lin, Shu-Ting; Huang, Yong; Zhang, Luoying; Heng, Mary Y; Ptácek, Louis J; Fu, Ying-Hui

    2013-10-22

    Demyelinating disorders including leukodystrophies are devastating conditions that are still in need of better understanding, and both oligodendrocyte differentiation and myelin synthesis pathways are potential avenues for developing treatment. Overexpression of lamin B1 leads to leukodystrophy characterized by demyelination of the central nervous system, and microRNA-23 (miR-23) was found to suppress lamin B1 and enhance oligodendrocyte differentiation in vitro. Here, we demonstrated that miR-23a-overexpressing mice have increased myelin thickness, providing in vivo evidence that miR-23a enhances both oligodendrocyte differentiation and myelin synthesis. Using this mouse model, we explored possible miR-23a targets and revealed that the phosphatase and tensin homologue/phosphatidylinositol trisphosphate kinase/Akt/mammalian target of rapamycin pathway is modulated by miR-23a. Additionally, a long noncoding RNA, 2700046G09Rik, was identified as a miR-23a target and modulates phosphatase and tensin homologue itself in a miR-23a-dependent manner. The data presented here imply a unique role for miR-23a in the coordination of proteins and noncoding RNAs in generating and maintaining healthy myelin. PMID:24101522

  14. Delayed myelination in an intrauterine growth retardation model is mediated by oxidative stress upregulating bone morphogenetic protein 4.

    PubMed

    Reid, Mary V; Murray, Kaitlin A; Marsh, Eric D; Golden, Jeffrey A; Simmons, Rebecca A; Grinspan, Judith B

    2012-07-01

    Intrauterine growth retardation (IUGR) is associated with neurological deficits including cerebral palsy and cognitive and behavioral disabilities. The pathogenesis involves oxidative stress that leads to periventricular white matter injury with a paucity of mature oligodendrocytes and hypomyelination. The molecular mechanisms underlying this damage remain poorly understood. We used a rat model of IUGR created by bilateral ligation of the uterine artery at embryonic Day 19 that results in fetal growth retardation and oxidative stress in the developing brain. The IUGR rat pups showed significant delays in oligodendrocyte differentiation and myelination that resolved by 8 weeks. Bone morphogenetic protein 4 (BMP4), which inhibits oligodendrocyte maturation, was elevated in IUGR brains at postnatal time points and returned to near normal by adulthood. Despite the apparent recovery, behavioral deficiencies were found in 8-week-old female animals, suggesting that the early transient myelination defects have permanent effects. In support of these in vivo data, oligodendrocyte precursor cells cultured from postnatal IUGR rats retained increased BMP4 expression and impaired differentiation that was reversed with the BMP inhibitor noggin. Oxidants in oligodendrocyte cultures increased BMP expression, which decreased differentiation; however, abrogating BMP signaling with noggin in vitro and in BMP-deficient mice prevented these effects. Together, these findings suggest that IUGR results in delayed myelination through the generation of oxidative stress that leads to BMP4 upregulation. PMID:22710965

  15. Treatment with Thyroxine Restores Myelination and Clinical Recovery after Intraventricular Hemorrhage

    PubMed Central

    Vose, Linnea R.; Vinukonda, Govindaiah; Jo, Sungro; Miry, Omid; Diamond, Daniel; Korumilli, Ritesh; Arshad, Arslan; Zia, Muhammad T. K.; Hu, Furong; Kayton, Robert J.; La Gamma, Edmund F.; Bansal, Rashmi; Bianco, Antonio C.

    2013-01-01

    Intraventricular hemorrhage (IVH) remains a major cause of white matter injury in preterm infants with no viable therapeutic strategy to restore myelination. Maturation of oligodendrocytes and myelination is influenced by thyroid hormone (TH) signaling, which is mediated by TH receptor α (TRα) and TRβ. In the brain, cellular levels of TH are regulated by deiodinases, with deiodinase-2 mediating TH activation and deiodinase-3 TH inactivation. Therefore, we hypothesized that IVH would decrease TH signaling via changes in the expression of deiodinases and/or TRs, and normalization of TH signaling would enhance maturation of oligodendrocytes and myelination in preterm infants with IVH. These hypotheses were tested using both autopsy materials from human preterm infants and a rabbit model of IVH. We found that deiodinase-2 levels were reduced, whereas deiodinase-3 levels were increased in brain samples of both humans and rabbits with IVH compared with controls without IVH. TRα expression was also increased in human infants with IVH. Importantly, treatment with TH accelerated the proliferation and maturation of oligodendrocytes, increased transcription of Olig2 and Sox10 genes, augmented myelination, and restored neurological function in pups with IVH. Consistent with these findings, the density of myelinating oligodendrocytes was almost doubled in TH-treated human preterm infants compared with controls. Thus, in infants with IVH the combined elevation in deiodinase-3 and reduction in deiodinase-2 decreases TH signaling that can be worsened by an increase in unliganded TRα. Given that TH promotes neurological recovery in IVH, TH treatment might improve the neurodevelopmental outcome of preterm infants with IVH. PMID:24174657

  16. Isolation and expansion of oligodendrocyte progenitor cells from cryopreserved human umbilical cord blood

    PubMed Central

    TRACY, ELISABETH T.; ZHANG, CLAIRE Y.; GENTRY, TRACY; SHOULARS, KEVIN W.; KURTZBERG, JOANNE

    2011-01-01

    Background aims Oligodendrocyte precursor cells (OPC) hold promise as a cellular therapy for demyelinating diseases. The feasibility of using OPC-based therapies in humans depends upon a reliable, readily available source. We have previously described the isolation, expansion and characterization of oligodendrocyte-like cells from fresh human umbilical cord blood (UCB). We now describe the isolation and expansion of OPC from thawed, cryopreserved UCB. Methods We thawed cryopreserved UCB units employing a standard clinical protocol, then isolated and plated mononuclear cells under previously established culture conditions. All OPC cultures were trypsinized at 21 days, counted, then characterized by flow cytometry after fixation, permeablization and labeling with the following antibodies: anti-oligodendrocyte marker 4 (O4), anti-oligodendrocyte marker 1 (O1) and anti-myelin basic protein (MBP). OPC were also placed in co-culture with shiverer mouse neuronal cells then stained in situ for beta tubulin III (BT3) and MBP as a functional assay of myelination. Results The average OPC yield per cryopreserved UCB unit was 64% of that seen with fresh UCB. On flow cytometric analysis, 74% of thawed UCB units yielded cells with an O4-expression level of at least 20% of total events, compared with 95% of fresh UCB units. We observed myelination of shiverer neurons in our functional assay, which could be used as a potency assay for release of OPC cells in phase I human clinical trials. Conclusions Our results demonstrate that OPC can be derived reliably from thawed, cryopreserved UCB units, and support the feasibility of using these cells in human clinical trials. PMID:21341973

  17. Preliminary Evidence of Increased Hippocampal Myelin Content in Veterans with Posttraumatic Stress Disorder

    PubMed Central

    Chao, Linda L.; Tosun, Duygu; Woodward, Steven H.; Kaufer, Daniela; Neylan, Thomas C.

    2015-01-01

    Recent findings suggest the formation of myelin in the central nervous system by oligodendrocytes is a continuous process that can be modified with experience. For example, a recent study showed that immobilization stress increased oligodendrogensis in the dentate gyrus of adult rat hippocampus. Because changes in myelination represents an adaptive form of brain plasticity that has a greater reach in the adult brain than other forms of plasticity (e.g., neurogenesis), the objective of this “proof of concept” study was to examine whether there are differences in myelination in the hippocampi of humans with and without post-traumatic stress disorder (PTSD). We used the ratio of T1-weighted/T2-weighted magnetic resonance image (MRI) intensity to estimate the degree of hippocampal myelination in 19 male veterans with PTSD and 19 matched trauma-exposed male veterans without PTSD (mean age: 43 ± 12 years). We found that veterans with PTSD had significantly more hippocampal myelin than trauma-exposed controls. There was also found a positive correlation between estimates of hippocampal myelination and PTSD and depressive symptom severity. To our knowledge, this is the first study to examine hippocampal myelination in humans with PTSD. These results provide preliminary evidence for stress-induced hippocampal myelin formation as a potential mechanism underlying the brain abnormalities associated with vulnerability to stress. PMID:26696852

  18. Histone Deacetylase 11 Regulates Oligodendrocyte-Specific Gene Expression and Cell Development in OL-1 Oligodendroglia Cells

    PubMed Central

    Liu, Hedi; Hu, Qichen; D’Ercole, A. Joseph; Ye, Ping

    2008-01-01

    Both in vivo and in vitro studies indicate a correlation between reduced acetylation of histone core proteins and oligodendrocyte development. The nature of these histone modifications and the mechanisms mediating them remain undefined. To address these issues we utilized OL-1 cells, a rat non-transformed oligodendrocyte cell line, and primary oligodendrocyte cultures. We found that the acetylated histone H3 at lysine 9 and lysine 14 (H3K9/K14ac) is reduced in both the myelin basic protein (MBP) and proteolipid protein (PLP) genes of maturing oligodendroglial OL-1 cells, and furthermore, this temporally correlates with increases in MBP, PLP, and histone deacetylase (HDAC) 11 expression. Disruption of developmentally-regulated histone H3 deacetylation within the MBP and PLP genes by the HDAC inhibitor trichostatin A blunts MBP and PLP expression. With its increased expression, interaction of HDAC 11 with acetylated histone H3 and recruitment of HDAC 11 to the MBP and PLP genes markedly increases in maturing OL-1 cells. Moreover, suppressing HDAC 11 expression with small interfering RNA significantly: 1) increases H3K9/K14ac globally and within the MBP and PLP genes, 2) decreases MBP and PLP mRNA expression, and 3) blunts the morphological changes associated with oligodendrocyte development. Our data strongly support a specific role for HDAC 11 in histone deacetylation and in turn the regulation of oligodendrocyte-specific protein gene expression and oligodendrocyte development. PMID:18627006

  19. Actomyosin contractility controls cell surface area of oligodendrocytes

    PubMed Central

    Kippert, Angelika; Fitzner, Dirk; Helenius, Jonne; Simons, Mikael

    2009-01-01

    Background To form myelin oligodendrocytes expand and wrap their plasma membrane multiple times around an axon. How is this expansion controlled? Results Here we show that cell surface area depends on actomyosin contractility and is regulated by physical properties of the supporting matrix. Moreover, we find that chondroitin sulfate proteoglycans (CSPG), molecules associated with non-permissive growth properties within the central nervous system (CNS), block cell surface spreading. Most importantly, the inhibitory effects of CSPG on plasma membrane extension were completely prevented by treatment with inhibitors of actomyosin contractility and by RNAi mediated knockdown of myosin II. In addition, we found that reductions of plasma membrane area were accompanied by changes in the rate of fluid-phase endocytosis. Conclusion In summary, our results establish a novel connection between endocytosis, cell surface extension and actomyosin contractility. These findings open up new possibilities of how to promote the morphological differentiation of oligodendrocytes in a non-permissive growth environment. See related minireview by Bauer and ffrench-Constant: PMID:19781079

  20. MHC Class I-Restricted Myelin Epitopes Are Cross-Presented by Tip-DCs That Promote Determinant Spreading to CD8+ T Cells

    PubMed Central

    Ji, Qingyong; Castelli, Luca; Goverman, Joan M.

    2013-01-01

    Myelin presentation to T cells within the central nervous system (CNS) sustains inflammation in multiple sclerosis (MS). CD4+ and CD8+ T cells contribute to MS; however, only cells that present myelin to CD4+ T cells have been identified. We show that MHC class I-restricted myelin basic protein (MBP) was presented by oligodendrocytes and cross-presented by Tip-dendritic cells (DCs) during experimental autoimmune encephalomyelitis (EAE), an animal model of MS initiated by CD4+ T cells. Tip-DCs activated naïve and effector CD8+ T cells ex vivo, and naïve MBP-specific CD8+ T cells were activated within the CNS during CD4+ T cell-induced EAE. These results demonstrate that CD4+ T cell-mediated CNS autoimmunity leads to determinant spreading to myelin-specific CD8+ T cells that are capable of direct recognition of oligodendrocytes. PMID:23291597

  1. Myelin basic protein synthesis is regulated by small non-coding RNA 715.

    PubMed

    Bauer, Nina M; Moos, Christina; van Horssen, Jack; Witte, Maarten; van der Valk, Paul; Altenhein, Benjamin; Luhmann, Heiko J; White, Robin

    2012-09-01

    Oligodendroglial Myelin Basic Protein (MBP) synthesis is essential for myelin formation in the central nervous system. During oligodendrocyte differentiation, MBP mRNA is kept in a translationally silenced state while intracellularly transported, until neuron-derived signals initiate localized MBP translation. Here we identify the small non-coding RNA 715 (sncRNA715) as an inhibitor of MBP translation. SncRNA715 localizes to cytoplasmic granular structures and associates with MBP mRNA transport granule components. We also detect increased levels of sncRNA715 in demyelinated chronic human multiple sclerosis lesions, which contain MBP mRNA but lack MBP protein. PMID:22744314

  2. Myelin Basic Protein synthesis is regulated by small non-coding RNA 715

    PubMed Central

    Bauer, Nina M; Moos, Christina; van Horssen, Jack; Witte, Maarten; van der Valk, Paul; Altenhein, Benjamin; Luhmann, Heiko J; White, Robin

    2012-01-01

    Oligodendroglial Myelin Basic Protein (MBP) synthesis is essential for myelin formation in the central nervous system. During oligodendrocyte differentiation, MBP mRNA is kept in a translationally silenced state while intracellularly transported, until neuron-derived signals initiate localized MBP translation. Here we identify the small non-coding RNA 715 (sncRNA715) as an inhibitor of MBP translation. SncRNA715 localizes to cytoplasmic granular structures and associates with MBP mRNA transport granule components. We also detect increased levels of sncRNA715 in demyelinated chronic human multiple sclerosis lesions, which contain MBP mRNA but lack MBP protein. PMID:22744314

  3. Vesicle transport in oligodendrocytes: probable role of Rab40c protein.

    PubMed

    Rodriguez-Gabin, A G; Almazan, G; Larocca, J N

    2004-06-15

    Intracellular membrane trafficking plays an essential role in the structural and functional organization of oligodendrocytes, which synthesize a large amount of membrane to form myelin. Rab proteins are key components in intracellular vesicular transport. We cloned a novel Rab protein from an oligodendrocyte cDNA library, designating it Rab40c because of its homology with Rab40a and Rab40b. The DNA sequence of Rab40c shows an 843-base pair open reading frame. The deduced amino acid sequence is a protein with 281 amino acids, with a molecular weight of 31,466 Da and an isoelectric point of 9.83. Rab40c presents a number of distinct structural features including a carboxyl terminal extension and amino acid substitutions in the consensus sequence of the GTP-binding motifs. The carboxyl terminal region contains motifs that permit isoprenylation and palmitoylation. Binding studies indicate that Rab40c binds guanosine 5'-0-(3-thiotriphosphate) (GTP gamma S) with a K(d) of 21 microM and has a higher affinity for guanosine triphosphate (GTP) than for guanosine diphosphate (GDP). Rab40c is localized in the perinuclear recycling compartment, suggesting its involvement in endocytic events such as receptor recycling. The importance of this recycling in myelin formation is suggested by the increase in both Rab40c mRNA and Rab40c protein as oligodendrocytes differentiate. PMID:15160388

  4. MyelStones: the executive roles of myelin basic protein in myelin assembly and destabilization in multiple sclerosis.

    PubMed

    Vassall, Kenrick A; Bamm, Vladimir V; Harauz, George

    2015-11-15

    The classic isoforms of myelin basic protein (MBP, 14-21.5 kDa) are essential to formation of the multilamellar myelin sheath of the mammalian central nervous system (CNS). The predominant 18.5-kDa isoform links together the cytosolic surfaces of oligodendrocytes, but additionally participates in cytoskeletal turnover and membrane extension, Fyn-mediated signalling pathways, sequestration of phosphoinositides and maintenance of calcium homoeostasis. All MBP isoforms are intrinsically disordered proteins (IDPs) that interact via molecular recognition fragments (MoRFs), which thereby undergo local disorder-to-order transitions. Their conformations and associations are modulated by environment and by a dynamic barcode of post-translational modifications, particularly phosphorylation by mitogen-activated and other protein kinases and deimination [a hallmark of demyelination in multiple sclerosis (MS)]. The MBPs are thus to myelin what basic histones are to chromatin. Originally thought to be merely structural proteins forming an inert spool, histones are now known to be dynamic entities involved in epigenetic regulation and diseases such as cancer. Analogously, the MBPs are not mere adhesives of compact myelin, but active participants in oligodendrocyte proliferation and in membrane process extension and stabilization during myelinogenesis. A central segment of these proteins is pivotal in membrane-anchoring and SH3 domain (Src homology 3) interaction. We discuss in the present review advances in our understanding of conformational conversions of this classic basic protein upon membrane association, including new thermodynamic analyses of transitions into different structural ensembles and how a shift in the pattern of its post-translational modifications is associated with the pathogenesis and potentially onset of demyelination in MS. PMID:26518750

  5. Dynamic expression of Cx47 in mouse brain development and in the cuprizone model of myelin plasticity.

    PubMed

    Parenti, Rosalba; Cicirata, Federico; Zappalà, Agata; Catania, Angela; La Delia, Francesco; Cicirata, Valentina; Tress, Oliver; Willecke, Klaus

    2010-10-01

    The study shows the dynamic expression of connexin47 (Cx47) in oligodendrocytes and myelin of mice, either in myelinogenesis occurring in early development or in an experimental model of new-myelinogenesis of adult mice. Cx47 first appeared in the embryonic mouse brain at E10.5 successively the expression increased, principally in regions populated by developing oligodendrocytes. The expression declined postnatally toward adulthood and immunoreactivity was restricted to a few specific areas, such as the corpus callosum, the striatum, the cerebellum, and the spinal cord. Since the expression of Cx47 in developing oligodendrocytes preceded those of Cx32 and Cx29, a role of Cx47 in myelinogenesis was postulated. This hypothesis was tested in a model of re-myelination, which principally involved the corpus callosum, occurring in adult mice by treatment with cuprizone. Cx47 was upregulated during demyelination and recovered during the remyelination phase. During demyelination, Cx47 was first over-expressed in the corpus callosum and later, when the myelin virtually disappeared in the injured areas, Cx47 was expressed in astrocytes located inside and closely around the demyelinated areas. The remyelination of injured areas occurred after stopping the administration of cuprizone and continued to complete recovery. In this period the expression of Cx47 shifted from astrocytes to newly-formed myelin. Thus, Cx47 exhibits in this model a transient and de novo expression in astrocytes with a topographic segregation in the injured areas, only when oligodendrocytes and the myelin were most severely affected. Taken as a whole the evidence suggests that Cx47 play a key role in myelination. PMID:20578039

  6. Myelin Lipid Abnormalities in the Aspartoacylase-Deficient Tremor Rat

    PubMed Central

    Wang, Jianfeng; Leone, Paola; Wu, Gusheng; Francis, Jeremy S.; Li, Hong; Jain, Mohit Raja; Serikawa, Tadao

    2015-01-01

    The high concentration of N-acetylaspartate (NAA) in neurons of the central nervous system and its growing clinical use as an indicator of neuronal viability has intensified interest in the biological function of this amino acid derivative. The biomedical relevance of such inquiries is highlighted by the myelin-associated pathology of Canavan disease, an inherited childhood disorder resulting from mutation of aspartoacylase (ASPA), the NAA-hydrolyzing enzyme. This enzyme is known to be localized in oligodendrocytes with bimodal distribution in cytosol and the myelin sheath, and to produce acetyl groups utilized in myelin lipid synthesis. Loss of this acetyl source in Canavan disease and rodent models such as the tremor rat are thought to account for the observed myelin deficit. This study was undertaken to further define and quantify the specific lipid abnormalities that occur as a result of ASPA deficit in the tremor rat. Employing mass spectrometry together with high performance thin-layer chromatography, we found that myelin from 28-day-old animals showed major reduction in cerebrosides (CB) and sulfatides (Sulf) with unsubstituted fatty acids, and equal if not greater changes in myelin from 7-month-old tremors. Cerebrosides with 2-hydroxyfatty acids showed little if any change at either age; Sulf with 2-hydroxyfatty acids showed no significant change at 28 days, but surprisingly a major increase at 7 months. Two species of phosphatidylcholine, 32:0 and 34:1, also showed significant increase, but only at 28 days. One form of phosphatidylethanolamine, PE36:1, was reduced a modest amount at both ages, whereas the plasmalogen form did not change. The dysmyelination that results from inactivation of ASPA is thus characterized by selective decreases as well as some increases in specific lipids. PMID:18478328

  7. Monoclonal antibody Rip specifically recognizes 2',3'-cyclic nucleotide 3'-phosphodiesterase in oligodendrocytes.

    PubMed

    Watanabe, Masatomo; Sakurai, Yoko; Ichinose, Tatsuya; Aikawa, Yoshikatsu; Kotani, Masaharu; Itoh, Kouichi

    2006-08-15

    The antigen recognized with monoclonal antibody (mAb) Rip (Rip-antigen) has been long used as a marker of oligodendrocytes and myelin sheaths. However, the identity of Rip-antigen has yet to be elucidated. We herein identified the Rip-antigen. No signal recognized by mAb-Rip was detected by immunoblot analyses in the rat brain, cultured rat oligodendrocytes, or the oligodendrocyte cell line CG-4. As this antibody worked very well on immunocytochemistry and immunohistochemistry, Rip-antigen was immunopurified with mAb-Rip from the differentiated CG-4 cells. Eight strong-intensity bands thus appeared on 5-20% SDS-PAGE with SYPRO ruby fluorescence staining. To identify these molecules, each band extracted from the gel was analyzed by MALDI-QIT/TOF mass spectrometry. We found an interesting molecule in the oligodendrocytes from an approximately 44-kDa band as 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP). To test whether CNP was recognized by mAb-Rip, double-immunofluorescence staining was performed by using Alexa Fluor 488-conjugated mAb-Rip and Alexa Fluor 568-conjugated mAb-CNP in the rat cerebellum, mouse cerebellum, cultured rat oligodendrocytes, and CG-4 cells. The Rip-antigen was colocalized with CNP in these cells and tissues. To provide direct evidence that CNP was recognized by mAb-Rip, rat Cnp1-transfected HEK293T cells were used for double-immunofluorescence staining with mAb-Rip and mAb-CNP. The Rip-antigen was colocalized with CNP in rat Cnp1-transfected HEK293T cells, but the antigen was not detected by mAb-Rip and mAb-CNP in mock-transfected HEK293T cells. Overall, we have demonstrated that the antigen labeled with mAb-Rip is CNP in the oligodendrocytes. PMID:16786579

  8. Myelination: Both Mindful and Mindless?

    PubMed

    Appel, Bruce

    2016-06-01

    The amount of myelin that forms on individual axons can vary considerably. Recent work, including a new study, indicates that myelin profiles on distinct subclasses of axons might be determined by diverse mechanisms. PMID:27269724

  9. Protandim Protects Oligodendrocytes against an Oxidative Insult.

    PubMed

    Lim, Jamie L; van der Pol, Susanne M A; Baron, Wia; McCord, Joe M; de Vries, Helga E; van Horssen, Jack

    2016-01-01

    Oligodendrocyte damage and loss are key features of multiple sclerosis (MS) pathology. Oligodendrocytes appear to be particularly vulnerable to reactive oxygen species (ROS) and cytokines, such as tumor necrosis factor-α (TNF), which induce cell death and prevent the differentiation of oligodendrocyte progenitor cells (OPCs). Here, we investigated the efficacy of sulforaphane (SFN), monomethyl fumarate (MMF) and Protandim to induce Nrf2-regulated antioxidant enzyme expression, and protect oligodendrocytes against ROS-induced cell death and ROS-and TNF-mediated inhibition of OPC differentiation. OLN-93 cells and primary rat oligodendrocytes were treated with SFN, MMF or Protandim resulting in significant induction of Nrf2-driven (antioxidant) proteins heme oygenase-1, nicotinamide adenine dinucleotide phosphate (NADPH): quinone oxidoreductase-1 and p62/SQSTM1, as analysed by Western blotting. After incubation with the compounds, oligodendrocytes were exposed to hydrogen peroxide. Protandim most potently promoted oligodendrocyte cell survival as measured by live/death viability assay. Moreover, OPCs were treated with Protandim or vehicle control prior to exposing them to TNF or hydrogen peroxide for five days, which inhibited OPC differentiation. Protandim significantly promoted OPC differentiation under influence of ROS, but not TNF. Protandim, a combination of five herbal ingredients, potently induces antioxidants in oligodendrocytes and is able to protect oligodendrocytes against oxidative stress by preventing ROS-induced cell death and promoting OPC differentiation. PMID:27618111

  10. Kif13b Regulates PNS and CNS Myelination through the Dlg1 Scaffold

    PubMed Central

    Noseda, Roberta; Guerrero-Valero, Marta; Alberizzi, Valeria; Previtali, Stefano C.; Sherman, Diane L.; Palmisano, Marilena; Huganir, Richard L.; Nave, Klaus-Armin; Cuenda, Ana; Feltri, Maria Laura; Brophy, Peter J.; Bolino, Alessandra

    2016-01-01

    Microtubule-based kinesin motors have many cellular functions, including the transport of a variety of cargos. However, unconventional roles have recently emerged, and kinesins have also been reported to act as scaffolding proteins and signaling molecules. In this work, we further extend the notion of unconventional functions for kinesin motor proteins, and we propose that Kif13b kinesin acts as a signaling molecule regulating peripheral nervous system (PNS) and central nervous system (CNS) myelination. In this process, positive and negative signals must be tightly coordinated in time and space to orchestrate myelin biogenesis. Here, we report that in Schwann cells Kif13b positively regulates myelination by promoting p38γ mitogen-activated protein kinase (MAPK)-mediated phosphorylation and ubiquitination of Discs large 1 (Dlg1), a known brake on myelination, which downregulates the phosphatidylinositol 3-kinase (PI3K)/v-AKT murine thymoma viral oncogene homolog (AKT) pathway. Interestingly, Kif13b also negatively regulates Dlg1 stability in oligodendrocytes, in which Dlg1, in contrast to Schwann cells, enhances AKT activation and promotes myelination. Thus, our data indicate that Kif13b is a negative regulator of CNS myelination. In summary, we propose a novel function for the Kif13b kinesin in glial cells as a key component of the PI3K/AKT signaling pathway, which controls myelination in both PNS and CNS. PMID:27070899

  11. Kif13b Regulates PNS and CNS Myelination through the Dlg1 Scaffold.

    PubMed

    Noseda, Roberta; Guerrero-Valero, Marta; Alberizzi, Valeria; Previtali, Stefano C; Sherman, Diane L; Palmisano, Marilena; Huganir, Richard L; Nave, Klaus-Armin; Cuenda, Ana; Feltri, Maria Laura; Brophy, Peter J; Bolino, Alessandra

    2016-04-01

    Microtubule-based kinesin motors have many cellular functions, including the transport of a variety of cargos. However, unconventional roles have recently emerged, and kinesins have also been reported to act as scaffolding proteins and signaling molecules. In this work, we further extend the notion of unconventional functions for kinesin motor proteins, and we propose that Kif13b kinesin acts as a signaling molecule regulating peripheral nervous system (PNS) and central nervous system (CNS) myelination. In this process, positive and negative signals must be tightly coordinated in time and space to orchestrate myelin biogenesis. Here, we report that in Schwann cells Kif13b positively regulates myelination by promoting p38γ mitogen-activated protein kinase (MAPK)-mediated phosphorylation and ubiquitination of Discs large 1 (Dlg1), a known brake on myelination, which downregulates the phosphatidylinositol 3-kinase (PI3K)/v-AKT murine thymoma viral oncogene homolog (AKT) pathway. Interestingly, Kif13b also negatively regulates Dlg1 stability in oligodendrocytes, in which Dlg1, in contrast to Schwann cells, enhances AKT activation and promotes myelination. Thus, our data indicate that Kif13b is a negative regulator of CNS myelination. In summary, we propose a novel function for the Kif13b kinesin in glial cells as a key component of the PI3K/AKT signaling pathway, which controls myelination in both PNS and CNS. PMID:27070899

  12. A new Cys2/His2 zinc finger gene, rKr1, expressed in oligodendrocytes and neurons.

    PubMed

    Pott, U; Colello, R J; Schwab, M E

    1996-05-01

    The myelination of nerve fibers is essential for the function of the vertebrate nervous system as a prerequisite for fast saltatory conduction of action potentials. In the central nervous system (CNS), myelin is produced by oligodendrocytes. In order to identify gene regulatory proteins involved in the differentiation of this glial cell type or in the expression of myelin-specific genes, we have constructed a cDNA library from a highly enriched population of rat oligodendrocytes and screened this library for members of the Krüppel family of Cys2/His2 zinc finger proteins. One of the identified clones, named rKr1, encodes a novel protein of 650 amino acids which contains 12 carboxy-terminal zinc finger domains and an amino-terminal acidic domain. On Northern blots, a single rKr1 mRNA of 4.3 kb is detected. This message is present in all adult rat tissues tested, with the highest levels found in the CNS and testis. In situ hybridization on the P15 brain revealed that the transcript is expressed in differentiated oligodendrocytes and in subtypes of neurons. Particularly high message levels are found in motor neurons of the brainstem and the spinal cord. The modular structure of the rKr1 protein, in which a potential DNA binding region (the zinc fingers) is combined with a putative activation domain (the acidic region), suggests a function as sequence-specific transcriptional activator. PMID:8737674

  13. Oligodendrocyte Precursor Cells in Spinal Cord Injury: A Review and Update

    PubMed Central

    Li, Ning; Leung, Gilberto K. K.

    2015-01-01

    Spinal cord injury (SCI) is a devastating condition to individuals, families, and society. Oligodendrocyte loss and demyelination contribute as major pathological processes of secondary damages after injury. Oligodendrocyte precursor cells (OPCs), a subpopulation that accounts for 5 to 8% of cells within the central nervous system, are potential sources of oligodendrocyte replacement after SCI. OPCs react rapidly to injuries, proliferate at a high rate, and can differentiate into myelinating oligodendrocytes. However, posttraumatic endogenous remyelination is rarely complete, and a better understanding of OPCs' characteristics and their manipulations is critical to the development of novel therapies. In this review, we summarize known characteristics of OPCs and relevant regulative factors in both health and demyelinating disorders including SCI. More importantly, we highlight current evidence on post-SCI OPCs transplantation as a potential treatment option as well as the impediments against regeneration. Our aim is to shed lights on important knowledge gaps and to provoke thoughts for further researches and the development of therapeutic strategies. PMID:26491661

  14. Proton-gated Ca2+-permeable TRP channels damage myelin in conditions mimicking ischaemia

    PubMed Central

    Hamilton, Nicola B.; Kolodziejczyk, Karolina; Kougioumtzidou, Eleni; Attwell, David

    2015-01-01

    The myelin sheaths wrapped around axons by oligodendrocytes are crucial for brain function. In ischaemia myelin is damaged in a Ca2+-dependent manner, abolishing action potential propagation1,2. This has been attributed to glutamate release activating Ca2+-permeable NMDA receptors2-4. Surprisingly, we now show that NMDA does not raise [Ca2+]i in mature oligodendrocytes and that, although ischaemia evokes a glutamate-triggered membrane current4, this is generated by a rise of extracellular [K+] and decrease of membrane K+ conductance. Nevertheless, ischaemia raises oligodendrocyte [Ca2+]i, [Mg2+]i and [H+]i, and buffering intracellular pH reduces the [Ca2+]i and [Mg2+]i increases, showing that these are evoked by the rise of [H+]i. The H+-gated [Ca2+]i elevation is mediated by channels with characteristics of TRPA1, being inhibited by ruthenium red, isopentenyl pyrophosphate, HC-030031, A967079 or TRPA1 knockout. TRPA1 block reduces myelin damage in ischaemia. These data suggest TRPA1-containing ion channels as a therapeutic target in white matter ischaemia. PMID:26760212

  15. CX3CL1/CX3CR1 Axis Plays a Key Role in Ischemia-Induced Oligodendrocyte Injury via p38MAPK Signaling Pathway.

    PubMed

    Wu, Xiao-Mei; Liu, Yong; Qian, Zhong-Ming; Luo, Qian-Qian; Ke, Ya

    2016-08-01

    Based on current knowledge on the role of the CX3CL1/CX3CR1 axis in the regulation of microglial activation and on the involvement of activated microglia in damaging oligodendrocytes, we hypothesized that CX3CL1/CX3CR1 axis is associated with the development of ischemic oligodendrocyte and white matter injury. We investigated the effects of CX3CL1, CX3CR1 shRNA, and p38MAPK inhibitor on the apoptosis, proliferation, and myelin proteolipid protein (PLP) expression in oligodendrocytes in co-cultures with BV2 microglia under ischemia. We demonstrated that CX3CL1 markedly increased the numbers of apoptotic oligodendrocytes, decreased PLP expression in oligodendrocytes, and inhibited the increased proliferation of oligodendrocytes induced by ischemia in co-cultures. All these effects of CX3CL1 were suppressed by pre-treatment of BV2 microglia with CX3CR1 shRNA to silence CX3CR1 expression or SB203580 to inhibit p38MAPK pathway. Our findings support that CX3CL1/CX3CR1 axis plays a key role in the development of ischemia-induced oligodendrocyte injury via p38MAPK signaling pathway. PMID:26189830

  16. Modulatory effects of oligodendrocytes on the conduction velocity of action potentials along axons in the alveus of the rat hippocampal CA1 region.

    PubMed

    Yamazaki, Yoshihiko; Hozumi, Yasukazu; Kaneko, Kenya; Sugihara, Toshimichi; Fujii, Satoshi; Goto, Kaoru; Kato, Hiroshi

    2007-11-01

    Like neurons and astrocytes, oligodendrocytes have a variety of neurotransmitter receptors and ion channels. However, except for facilitating the rapid conduction of action potentials by forming myelin and buffering extracellular K(+), little is known about the direct involvement of oligodendrocytes in neuronal activities. To investigate their physiological roles, we focused on oligodendrocytes in the alveus of the rat hippocampal CA1 region. These cells were found to respond to exogenously applied glutamate by depolarization through N-methyl-D-aspartate (NMDA) receptors and non-NMDA receptors. Electrical stimulation of the border between the alveus and stratum oriens evoked inward currents through several routes involving glutamate receptors and inward rectifier K(+) channels. Moreover, electrical stimulation resembling in vivo activity evoked long-lasting depolarization. To examine the modulatory effects of oligodendrocytes on neuronal activities, we performed dual, whole-cell recording on CA1 pyramidal neurons and oligodendrocytes. Direct depolarization of oligodendrocytes shortened the latencies of action potentials evoked by antidromic stimulation. These results indicate that oligodendrocytes increase the conduction velocity of action potentials by a mechanism additional to saltatory conduction, and that they have active roles in information processing in the brain. PMID:18634564

  17. Kappa opioid receptor activation alleviates experimental autoimmune encephalomyelitis and promotes oligodendrocyte-mediated remyelination

    PubMed Central

    Du, Changsheng; Duan, Yanhui; Wei, Wei; Cai, Yingying; Chai, Hui; Lv, Jie; Du, Xiling; Zhu, Jian; Xie, Xin

    2016-01-01

    Multiple sclerosis (MS) is characterized by autoimmune damage to the central nervous system. All the current drugs for MS target the immune system. Although effective in reducing new lesions, they have limited effects in preventing the progression of disability. Promoting oligodendrocyte-mediated remyelination and recovery of neurons are the new directions of MS therapy. The endogenous opioid system, consisting of MOR, DOR, KOR and their ligands, has been suggested to participate in the pathogenesis of MS. However, the exact receptor and mechanism remain elusive. Here we show that genetic deletion of KOR exacerbates experimental autoimmune encephalomyelitis, whereas activating KOR with agonists alleviates the symptoms. KOR does not affect immune cell differentiation and function. Instead, it promotes oligodendrocyte differentiation and myelination both in vitro and in vivo. Our study suggests that targeting KOR might be an intriguing way to develop new MS therapies that may complement the existing immunosuppressive approaches. PMID:27040771

  18. Kappa opioid receptor activation alleviates experimental autoimmune encephalomyelitis and promotes oligodendrocyte-mediated remyelination.

    PubMed

    Du, Changsheng; Duan, Yanhui; Wei, Wei; Cai, Yingying; Chai, Hui; Lv, Jie; Du, Xiling; Zhu, Jian; Xie, Xin

    2016-01-01

    Multiple sclerosis (MS) is characterized by autoimmune damage to the central nervous system. All the current drugs for MS target the immune system. Although effective in reducing new lesions, they have limited effects in preventing the progression of disability. Promoting oligodendrocyte-mediated remyelination and recovery of neurons are the new directions of MS therapy. The endogenous opioid system, consisting of MOR, DOR, KOR and their ligands, has been suggested to participate in the pathogenesis of MS. However, the exact receptor and mechanism remain elusive. Here we show that genetic deletion of KOR exacerbates experimental autoimmune encephalomyelitis, whereas activating KOR with agonists alleviates the symptoms. KOR does not affect immune cell differentiation and function. Instead, it promotes oligodendrocyte differentiation and myelination both in vitro and in vivo. Our study suggests that targeting KOR might be an intriguing way to develop new MS therapies that may complement the existing immunosuppressive approaches. PMID:27040771

  19. Activation of Sterol Regulatory Element Binding Factors by Fenofibrate and Gemfibrozil Stimulates Myelination in Zebrafish

    PubMed Central

    Ashikawa, Yoshifumi; Nishimura, Yuhei; Okabe, Shiko; Sasagawa, Shota; Murakami, Soichiro; Yuge, Mizuki; Kawaguchi, Koki; Kawase, Reiko; Tanaka, Toshio

    2016-01-01

    Oligodendrocytes are major myelin-producing cells and play essential roles in the function of a healthy nervous system. However, they are also one of the most vulnerable neural cell types in the central nervous system (CNS), and myelin abnormalities in the CNS are found in a wide variety of neurological disorders, including multiple sclerosis, adrenoleukodystrophy, and schizophrenia. There is an urgent need to identify small molecular weight compounds that can stimulate myelination. In this study, we performed comparative transcriptome analysis to identify pharmacodynamic effects common to miconazole and clobetasol, which have been shown to stimulate myelination by mouse oligodendrocyte progenitor cells (OPCs). Of the genes differentially expressed in both miconazole- and clobetasol-treated mouse OPCs compared with untreated cells, we identified differentially expressed genes (DEGs) common to both drug treatments. Gene ontology analysis revealed that these DEGs are significantly associated with the sterol biosynthetic pathway, and further bioinformatics analysis suggested that sterol regulatory element binding factors (SREBFs) might be key upstream regulators of the DEGs. In silico screening of a public database for chemicals associated with SREBF activation identified fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) agonist, as a drug that increases the expression of known SREBF targets, raising the possibility that fenofibrate may also stimulate myelination. To test this, we performed in vivo imaging of zebrafish expressing a fluorescent reporter protein under the control of the myelin basic protein (mbp) promoter. Treatment of zebrafish with fenofibrate significantly increased expression of the fluorescent reporter compared with untreated zebrafish. This increase was attenuated by co-treatment with fatostatin, a specific inhibitor of SREBFs, confirming that the fenofibrate effect was mediated via SREBFs. Furthermore, incubation of zebrafish

  20. MAL Is a Regulator of the Recruitment of Myelin Protein PLP to Membrane Microdomains

    PubMed Central

    Bijlard, Marjolein; de Jonge, Jenny C.; Klunder, Bert; Nomden, Anita; Hoekstra, Dick; Baron, Wia

    2016-01-01

    In oligodendrocytes (OLGs), an indirect, transcytotic pathway is mediating transport of de novo synthesized PLP, a major myelin specific protein, from the apical-like plasma membrane to the specialized basolateral-like myelin membrane to prevent its premature compaction. MAL is a well-known regulator of polarized trafficking in epithelial cells, and given its presence in OLGs it was therefore of interest to investigate whether MAL played a similar role in PLP transport in OLGs, taking into account its timely expression in these cells. Our data revealed that premature expression of mCherry-MAL in oligodendrocyte progenitor cells interfered with terminal OLG differentiation, although myelin membrane formation per se was not impaired. In fact, also PLP transport to myelin membranes via the cell body plasma membrane was unaffected. However, the typical shift of PLP from TX-100-insoluble membrane domains to CHAPS-resistant, but TX-100-soluble membrane domains, seen in the absence of MAL expression, is substantially reduced upon expression of the MAL protein. Interestingly, not only in vitro, but also in developing brain a strongly diminished shift from TX-100 resistant to TX-100 soluble domains was observed. Consistently, the MAL-expression mediated annihilation of the typical membrane microdomain shift of PLP is also reflected by a loss of the characteristic surface expression profile of conformation-sensitive anti-PLP antibodies. Hence, these findings suggest that MAL is not involved in vesicular PLP trafficking to either the plasma membrane and/or the myelin membrane as such. Rather, we propose that MAL may regulate PLP’s distribution into distinct membrane microdomains that allow for lateral diffusion of PLP, directly from the plasma membrane to the myelin membrane once the myelin sheath has been assembled. PMID:27171274

  1. Components of Myelin Damage and Repair in the Progression of White Matter Pathology After Mild Traumatic Brain Injury

    PubMed Central

    Mierzwa, Amanda J.; Marion, Christina M.; Sullivan, Genevieve M.; McDaniel, Dennis P.; Armstrong, Regina C.

    2015-01-01

    Abstract White matter tracts are highly vulnerable to damage from impact-acceleration forces of traumatic brain injury (TBI). Mild TBI is characterized by a low density of traumatic axonal injury, whereas associated myelin pathology is relatively unexplored. We examined the progression of white matter pathology in mice after mild TBI with traumatic axonal injury localized in the corpus callosum. Adult mice received a closed-skull impact and were analyzed from 3 days to 6 weeks post-TBI/sham surgery. At all times post-TBI, electron microscopy revealed degenerating axons distributed among intact fibers in the corpus callosum. Intact axons exhibited significant demyelination at 3 days followed by evidence of remyelination at 1 week. Accordingly, bromodeoxyuridine pulse-chase labeling demonstrated the generation of new oligodendrocytes, identified by myelin proteolipid protein messenger RNA expression, at 3 days post-TBI. Overall oligodendrocyte populations, identified by immunohistochemical staining for CC1 and/or glutathione S-transferase pi, were similar between TBI and sham mice by 2 weeks. Excessively long myelin figures, similar to redundant myelin sheaths, were a significant feature at all post-TBI time points. At 6 weeks post-TBI, microglial activation and astrogliosis were localized to areas of axon and myelin pathology. These studies show that demyelination, remyelination, and excessive myelin are components of white matter degeneration and recovery in mild TBI with traumatic axonal injury. PMID:25668562

  2. What is myelin?

    PubMed

    Hartline, Daniel K

    2008-05-01

    The evolution of a character is better appreciated if examples of convergent emergence of the same character are available for comparison. Three instances are known among invertebrates of the evolution of axonal sheaths possessing the functional properties and many of the structural properties of vertebrate myelin. Comparison of these invertebrate myelins raises the question of what structural features must a sheath possess in order to produce the two principal functional characteristics of impulse speed enhancement and energy savings. This essay reviews the features recognized by early workers as pertaining to myelin in vertebrate and invertebrate alike: osmiophilia, negative birefringence and saltatory conduction. It then examines common features revealed by the advent of electron microscopy: multiplicity of lipid membranes, condensation of those membranes, specialized marginal seals, and nodes. Next it examines the robustness of these features as essential components of a speed-enhancing sheath. Features that are not entirely essential for speed enhancement include membrane compaction, spiral wrapping of layers, glial cell involvement, non-active axonal membrane, and even nodes and perinodal sealing. This permissiveness is discussed in relation to the possible evolutionary origin of myelin. PMID:19737435

  3. On the Occurrence of Hypomyelination in a Transgenic Mouse Model: A Consequence of the Myelin Basic Protein Promoter?

    PubMed Central

    Gaupp, Stefanie; Arezzo, Joseph; Dutta, Dipankar J.; John, Gareth R.; Raine, Cedric S.

    2013-01-01

    Central nervous system hypomyelination is a feature common to a number of transgenic (Tg) mouse lines that express a variety of unrelated exogenous (i.e. non-CNS) transgenes. In this report we document hypomyelination structurally by immunocytochemistry and functionally in the Tg line MBP-JE, which overexpresses the chemokine CCL2 (MCP-1) within oligodendrocytes targeted by a myelin basic protein (MBP) promoter. Analysis of hypomyelinated optic nerves of Tg mice revealed progressive decrease in oligodendrocyte numbers with age (p < 0.01). Although molecular mechanisms underlying hypomyelination in this and other Tg models remain largely unknown, we present preliminary findings on oligodendrocyte progenitor cell (OPC) cultures in which, although OPC expressed CCR2, the receptor for CCL2, treatment with CCL2 had no significant effect on OPC proliferation, differentiation or apoptosis. We suggest that hypomyelination in the MBP-JE model might not be due to CCL2 expression but rather the result of transcriptional dysfunction related to random insertion of the MBP promoter that disrupts myelinogenesis and leads to oligodendrocytes demise. Because an MBP promoter is a common denominator in most Tg lines displaying hypomyelination, we hypothesize that use of myelin gene sequences in the regulator region of transgenic constructs might underlie this perturbation of myelination in such models. PMID:22082665

  4. Oct4 transcription factor in conjunction with valproic acid accelerates myelin repair in demyelinated optic chiasm in mice.

    PubMed

    Dehghan, S; Hesaraki, M; Soleimani, M; Mirnajafi-Zadeh, J; Fathollahi, Y; Javan, M

    2016-03-24

    Multiple sclerosis is a demyelinating disease with severe neurological symptoms due to blockage of signal conduction in affected axons. Spontaneous remyelination via endogenous progenitors is limited and eventually fails. Recent reports showed that forced expression of some transcription factors within the brain converted somatic cells to neural progenitors and neuroblasts. Here, we report the effect of valproic acid (VPA) along with forced expression of Oct4 transcription factor on lysolecithin (LPC)-induced experimental demyelination. Mice were gavaged with VPA for one week, and then inducible Oct4 expressing lentiviral particles were injected into the lateral ventricle. After one-week induction of Oct4, LPC was injected into the optic chiasm. Functional remyelination was assessed by visual-evoked potential (VEP) recording. Myelination level was studied using FluoroMyelin staining and immunohistofluorescent (IHF) against proteolipid protein (PLP). IHF was also performed to detect Oct4 and SSEA1 as pluripotency markers and Olig2, Sox10, CNPase and PDGFRα as oligodendrocyte lineage markers. One week after injection of Oct4 expressing vector, pluripotency markers SSEA1 and Oct4 were detected in the rims of the 3rd ventricle. LPC injection caused extensive demyelination and significantly delayed the latency of VEP wave. Animals pre-treated with VPA+Oct4 expressing vector, showed faster recovery in the VEP latency and enhanced myelination. Immunostaining against oligodendrocyte lineage markers showed an increased number of Sox10+ and myelinating cells. Moreover, transdifferentiation of some Oct4-transfected cells (GFP+ cells) to Olig2+ and CNPase+ cells was confirmed by immunostaining. One-week administration of VPA followed by one-week forced expression of Oct4 enhanced myelination by converting transduced cells to myelinating oligodendrocytes. This finding seems promising for enhancing myelin repair within the adult brains. PMID:26804242

  5. IκB kinase 2 determines oligodendrocyte loss by non-cell-autonomous activation of NF-κB in the central nervous system

    PubMed Central

    Raasch, Jenni; Zeller, Nicolas; van Loo, Geert; Merkler, Doron; Mildner, Alexander; Erny, Daniel; Knobeloch, Klaus-Peter; Bethea, John R.; Waisman, Ari; Knust, Markus; Del Turco, Domenico; Deller, Thomas; Blank, Thomas; Priller, Josef; Brück, Wolfgang

    2011-01-01

    The IκB kinase complex induces nuclear factor kappa B activation and has recently been recognized as a key player of autoimmunity in the central nervous system. Notably, IκB kinase/nuclear factor kappa B signalling regulates peripheral myelin formation by Schwann cells, however, its role in myelin formation in the central nervous system during health and disease is largely unknown. Surprisingly, we found that brain-specific IκB kinase 2 expression is dispensable for proper myelin assembly and repair in the central nervous system, but instead plays a fundamental role for the loss of myelin in the cuprizone model. During toxic demyelination, inhibition of nuclear factor kappa B activation by conditional ablation of IκB kinase 2 resulted in strong preservation of central nervous system myelin, reduced expression of proinflammatory mediators and a significantly attenuated glial response. Importantly, IκB kinase 2 depletion in astrocytes, but not in oligodendrocytes, was sufficient to protect mice from myelin loss. Our results reveal a crucial role of glial cell-specific IκB kinase 2/nuclear factor kappa B signalling for oligodendrocyte damage during toxic demyelination. Thus, therapies targeting IκB kinase 2 function in non-neuronal cells may represent a promising strategy for the treatment of distinct demyelinating central nervous system diseases. PMID:21310728

  6. Molecular anatomy and genetics of myelin proteins in the peripheral nervous system.

    PubMed Central

    Snipes, G J; Suter, U

    1995-01-01

    Myelin contains a number of proteins, the major examples of which are protein zero (Po), P2 protein, peripheral myelin protein 22 (PMP22), myelin basic proteins (MBPs), myelin-associated glycoprotein (MAG) and the recently described connexin 32 (Cx32). This list is probably still incomplete. The localisation and possible functions of these proteins are reviewed. In the past few years a number of inherited demyelinating neuropathies in mice and the human have been shown to be due to mutations affecting the genes PMP22, Po and Cx32 so that it has become possible to characterise the molecular pathology of the majority of these disorders. This has provided important insights into the relationships between the structure of myelin and the function of its constituent proteins. Images Fig. 1 PMID:7559122

  7. NMDA Receptors: Power Switches for Oligodendrocytes.

    PubMed

    Krasnow, Anna M; Attwell, David

    2016-07-01

    The role of NMDA receptors in oligodendrocytes has been controversial. A new paper (Saab et al., 2016) suggests they play a key role in regulating glucose uptake in response to axonal glutamate release, thus controlling metabolic cooperation between oligodendrocytes and axons. PMID:27387644

  8. Indian hedgehog B function is required for the specification of oligodendrocyte progenitor cells in the zebrafish CNS.

    PubMed

    Chung, Ah-Young; Kim, Suhyun; Kim, Eunmi; Kim, Dohyun; Jeong, Inyoung; Cha, Young Ryun; Bae, Young-ki; Park, Seung Woo; Lee, Jehee; Park, Hae-Chul

    2013-01-23

    A subset of ventral spinal cord precursors, known as pMN precursor cells, initially generate motor neurons and then oligodendrocyte progenitor cells (OPCs), which migrate and differentiate as myelinating oligodendrocytes in the developing neural tube. The switch between motor neuron and oligodendrocyte production by the pMN neural precursors is an important step in building a functional nervous system. However, the precise mechanism that orchestrates the sequential generation of motor neurons and oligodendrocytes within the common population of pMN precursors is still unclear. The current study demonstrates that Indian Hedgehog b (Ihhb), previously known as Echidna Hedgehog, begins to be expressed in the floor plate cells of the ventral spinal cord at the time of OPC specification in zebrafish embryos. Ihhb loss-of-function analysis revealed that Ihhb function is required for OPC specification from pMN precursors by negatively regulating the proliferation of neural precursors. Finally, results showed that Sonic Hedgehog (Shh) could not replace Ihhb function in OPC specification, suggesting that Ihhb and Shh play separate roles in OPC specification. Altogether, data from the present study suggested a novel mechanism, mediated by Ihhb, for the sequential generation of motor neurons and oligodendrocytes from pMN precursors in the ventral spinal cord of zebrafish embryos. PMID:23345245

  9. Decreased Oligodendrocyte and Neuron Number in Anterior Hippocampal Areas and the Entire Hippocampus in Schizophrenia: A Stereological Postmortem Study.

    PubMed

    Falkai, Peter; Malchow, Berend; Wetzestein, Katharina; Nowastowski, Verena; Bernstein, Hans-Gert; Steiner, Johann; Schneider-Axmann, Thomas; Kraus, Theo; Hasan, Alkomiet; Bogerts, Bernhard; Schmitz, Christoph; Schmitt, Andrea

    2016-07-01

    The hippocampus is involved in cognition as well as emotion, with deficits in both domains consistently described in schizophrenia. Moreover, the whole volumes of both the anterior and posterior region have been reported to be decreased in schizophrenia patients. While fewer oligodendrocyte numbers in the left and right cornu ammonis CA4 subregion of the posterior part of the hippocampus have been reported, the aim of this stereological study was to investigate cell numbers in either the dentate gyrus (DG) or subregions of the anterior hippocampus. In this design-based stereological study of the anterior part of the hippocampus comparing 10 patients with schizophrenia to 10 age- and gender-matched healthy controls were examined. Patients showed a decreased number of oligodendrocytes in the left CA4, fewer neurons in the left DG and smaller volumes in both the left CA4 and DG, which correlated with oligodendrocyte and neuron numbers, respectively. When exploring the total hippocampus, keeping previously published own results from the posterior part of the same brains in mind, both decreased oligodendrocyte numbers in the left CA4 and reduced volume remained significant. The decreased oligodendrocyte number speaks for a deficit in myelination and connectivity in schizophrenia which may originate from disturbed maturational processes. The reduced neuron number of the DG in the anterior hippocampus may well point to a reduced capacity of this region to produce new neurons up to adulthood. Both mechanisms may be involved in cognitive dysfunction in schizophrenia patients. PMID:27460617

  10. Altered PLP1 splicing causes hypomyelination of early myelinating structures

    PubMed Central

    Kevelam, Sietske H; Taube, Jennifer R; van Spaendonk, Rosalina M L; Bertini, Enrico; Sperle, Karen; Tarnopolsky, Mark; Tonduti, Davide; Valente, Enza Maria; Travaglini, Lorena; Sistermans, Erik A; Bernard, Geneviève; Catsman-Berrevoets, Coriene E; van Karnebeek, Clara D M; Østergaard, John R; Friederich, Richard L; Fawzi Elsaid, Mahmoud; Schieving, Jolanda H; Tarailo-Graovac, Maja; Orcesi, Simona; Steenweg, Marjan E; van Berkel, Carola G M; Waisfisz, Quinten; Abbink, Truus E M; van der Knaap, Marjo S; Hobson, Grace M; Wolf, Nicole I

    2015-01-01

    Objective The objective of this study was to investigate the genetic etiology of the X-linked disorder “Hypomyelination of Early Myelinating Structures” (HEMS). Methods We included 16 patients from 10 families diagnosed with HEMS by brain MRI criteria. Exome sequencing was used to search for causal mutations. In silico analysis of effects of the mutations on splicing and RNA folding was performed. In vitro gene splicing was examined in RNA from patients’ fibroblasts and an immortalized immature oligodendrocyte cell line after transfection with mutant minigene splicing constructs. Results All patients had unusual hemizygous mutations of PLP1 located in exon 3B (one deletion, one missense and two silent), which is spliced out in isoform DM20, or in intron 3 (five mutations). The deletion led to truncation of PLP1, but not DM20. Four mutations were predicted to affect PLP1/DM20 alternative splicing by creating exonic splicing silencer motifs or new splice donor sites or by affecting the local RNA structure of the PLP1 splice donor site. Four deep intronic mutations were predicted to destabilize a long-distance interaction structure in the secondary PLP1 RNA fragment involved in regulating PLP1/DM20 alternative splicing. Splicing studies in fibroblasts and transfected cells confirmed a decreased PLP1/DM20 ratio. Interpretation Brain structures that normally myelinate early are poorly myelinated in HEMS, while they are the best myelinated structures in Pelizaeus–Merzbacher disease, also caused by PLP1 alterations. Our data extend the phenotypic spectrum of PLP1-related disorders indicating that normal PLP1/DM20 alternative splicing is essential for early myelination and support the need to include intron 3 in diagnostic sequencing. PMID:26125040

  11. Proteomic Analysis of Nuclear Factors Binding to an Intronic Enhancer in the Myelin Proteolipid Protein Gene

    PubMed Central

    Dobretsova, Anna; Johnson, Jennifer W.; Jones, Richard C.; Edmondson, Ricky D.; Wight, Patricia A.

    2015-01-01

    The myelin proteolipid protein gene (Plp1) encodes the most abundant protein found in CNS myelin, accounting for nearly one-half of the total protein. Its expression in oligodendrocytes is developmentally regulated – peaking during the active myelination period of CNS development. Previously we have identified a novel enhancer (designated ASE) in intron 1 DNA that appears to be important in mediating the surge of Plp1 gene activity during the active myelination period. Evidence suggests that the ASE participates in the formation of a specialized multi-protein/DNA complex called an enhanceosome. The current study describes an optimized, five-step, DNA affinity chromatography purification procedure to purify nuclear proteins from mouse brain that bind to the 85-bp ASE sequence, specifically. EMSA analysis demonstrated that specific DNA binding activity was retained throughout the purification procedure, resulting in concomitant enrichment of nucleoprotein complexes. Identification of the purported regulatory factors was achieved through mass spectrometry analysis and included over twenty sequence-specific DNA-binding proteins. Supplementary Western blot analyses to determine which of these sequence-specific factors are present in oligodendrocytes, and their developmental and regional expression in whole brain, suggest that Purα and Purβ rank highest among the candidate factors as constituents of the multi-protein complex formed on the ASE. PMID:18266931

  12. Hypothyroxinemia induced by maternal mild iodine deficiency impairs hippocampal myelinated growth in lactational rats.

    PubMed

    Wei, Wei; Wang, Yi; Dong, Jing; Wang, Yuan; Min, Hui; Song, Binbin; Shan, Zhongyan; Teng, Weiping; Xi, Qi; Chen, Jie

    2015-11-01

    Hypothyroxinemia induced by maternal mild iodine deficiency causes neurological deficits and impairments of brain function in offspring. Hypothyroxinemia is prevalent in developing and developed countries alike. However, the mechanism underlying these deficits remains less well known. Given that the myelin plays an important role in learning and memory function, we hypothesize that hippocampal myelinated growth may be impaired in rat offspring exposed to hypothyroxinemia induced by maternal mild iodine deficiency. To test this hypothesis, the female Wistar rats were used and four experimental groups were prepared: (1) control; (2) maternal mild iodine deficiency diet inducing hypothyroxinemia; (3) hypothyroidism induced by maternal severe iodine deficiency diet; (4) hypothyroidism induced by maternal methimazole water. The rats were fed the diet from 3 months before pregnancy to the end of lactation. Our results showed that the physiological changes occuring in the hippocampal myelin were altered in the mild iodine deficiency group as indicated by the results of immunofluorescence of myelin basic proteins on postnatal day 14 and postnatal day 21. Moreover, hypothyroxinemia reduced the expressions of oligodendrocyte lineage transcription factor 2 and myelin-related proteins in the treatments on postnatal day 14 and postnatal day 21. Our data suggested that hypothyroxinemia induced by maternal mild iodine deficiency may impair myelinated growth of the offspring. PMID:24753110

  13. Impaired myelination and reduced brain ferric iron in the mouse model of mucolipidosis IV

    PubMed Central

    Grishchuk, Yulia; Peña, Karina A.; Coblentz, Jessica; King, Victoria E.; Humphrey, Daniel M.; Wang, Shirley L.; Kiselyov, Kirill I.; Slaugenhaupt, Susan A.

    2015-01-01

    ABSTRACT Mucolipidosis type IV (MLIV) is a lysosomal storage disease caused by mutations in the MCOLN1 gene, which encodes the lysosomal transient receptor potential ion channel mucolipin-1 (TRPML1). MLIV causes impaired motor and cognitive development, progressive loss of vision and gastric achlorhydria. How loss of TRPML1 leads to severe psychomotor retardation is currently unknown, and there is no therapy for MLIV. White matter abnormalities and a hypoplastic corpus callosum are the major hallmarks of MLIV brain pathology. Here, we report that loss of TRPML1 in mice results in developmental aberrations of brain myelination as a result of deficient maturation and loss of oligodendrocytes. Defective myelination is evident in Mcoln1−/− mice at postnatal day 10, an active stage of postnatal myelination in the mouse brain. Expression of mature oligodendrocyte markers is reduced in Mcoln1−/− mice at postnatal day 10 and remains lower throughout the course of the disease. We observed reduced Perls' staining in Mcoln1−/− brain, indicating lower levels of ferric iron. Total iron content in unperfused brain is not significantly different between Mcoln1−/− and wild-type littermate mice, suggesting that the observed maturation delay or loss of oligodendrocytes might be caused by impaired iron handling, rather than by global iron deficiency. Overall, these data emphasize a developmental rather than a degenerative disease course in MLIV, and suggest that there should be a stronger focus on oligodendrocyte maturation and survival to better understand MLIV pathogenesis and aid treatment development. PMID:26398942

  14. Microfabricated multi-electrode device for detecting oligodendrocyte-regulated changes in axonal conduction velocity.

    PubMed

    Sakai, Koji; Shimba, Kenta; Kotani, Kiyoshi; Jimbo, Yasuhiko

    2015-08-01

    Myelin disorders cause cognitive dysfunction, but little is known about how abnormal myelin sheath affects neural activities at the network level. One reason for the lack is a technical difficulty in simultaneous monitoring of changes in both the axonal conduction and network activity. Then, we aimed to develop a culture device to detect myelination dependent changes in axonal conduction velocity in a neuronal network. The photolithographically fabricated device has microtunnels for guiding axons. Two microelectrodes and an oligodendrocyte (OL) culture compartment are set at each microtunnel. This configuration allows us to monitor changes in conduction velocity of axons wrapped by OLs. Neurons and OLs dissected from rat cortical tissues were cultured in the culture device. An immunocytochemical study indicated axonal growth and maturation of OL at 42 days in vitro (DIV), suggesting that neuron-OL co-culture was maintained in microtunnels. Propagating action potentials of individual axons were detected from spontaneous neural activities with a spike sorting method and their conduction velocities were examined. Conduction velocity without seeding OLs was 0.31 m/s, which was consistent with that of previous reports with unmyelinated axons. Although no apparent myelin sheath was observed in OL culture compartments, conduction delay with seeding OLs was approximately half as long as that without seeding OLs at 45 DIV. These results suggest that the culture device enables us to detect the OL-regulated changes in axonal conduction in the neuronal network. PMID:26737935

  15. Myelin changes in leprous neuropathy.

    PubMed

    Jacobs, J M; Shetty, V P; Antia, N H

    1987-01-01

    Myelin changes were observed in fibres of nerves from cases of leprosy. The myelin had a 'loosened' appearance caused by increased and irregular separation of the intraperiod line. 'Loosening' might affect all, or only some, of the lamellae forming a myelin sheath. There was a patchy distribution of fibres with abnormal myelin, and they were seen only in nerves showing other marked pathological changes including the presence of oedema. The appearances are suggestive of intramyelinic oedema which may be related to the presence of endoneurial oedema. PMID:2821728

  16. Preparation of Rat Oligodendrocyte Progenitor Cultures and Quantification of Oligodendrogenesis Using Dual-infrared Fluorescence Scanning.

    PubMed

    Schott, Jason T; Kirby, Leslie A; Calabresi, Peter A; Baxi, Emily G

    2016-01-01

    Efficient oligodendrogenesis is the therapeutic goal of a number of areas of research including spinal cord injury, neonatal hypoxia, and demyelinating diseases such as multiple sclerosis and transverse myelitis. Myelination is required to not only facilitate rapid impulse propagation within the central nervous system, but also to provide trophic support to underlying axons. Oligodendrocyte progenitor cells (OPCs) can be studied in vitro to help identify factors that may promote or inhibit oligodendrocyte differentiation. To date, many of the methods available to evaluate this process have either required large numbers of cells, thus limiting the number of conditions that can be investigated at any one time, or labor-intensive methods of quantification. Herein, we describe a protocol for the isolation of large numbers of highly pure OPCs together with a fast and reliable method to determine oligodendrogenesis from multiple conditions simultaneously. OPCs are isolated from P5-P7 neonatal rat cortices and grown in vitro for three days prior to differentiation. Four days after differentiation, oligodendrogenesis is evaluated using a dual-infrared fluorescence-scanning assay to determine expression of the myelin protein. PMID:26967760

  17. Thymosin beta 4 mediates oligodendrocyte differentiation by upregulating p38 MAPK

    PubMed Central

    Santra, Manoranjan; Chopp, Michael; Zhang, Zheng Gang; Lu, Mei; Santra, Sutapa; Nalani, Ankita; Santra, Soumi; Morris, Daniel C.

    2013-01-01

    Thymosin beta 4 (Tβ4), a G-actin sequestering peptide, increases oligodendrogenesis and improves functional outcome in models of neurological injury. The molecular mechanisms of Tβ4 mediated oligodendrogenesis are unclear. The p38 mitogen-activated protein kinase (p38MAPK) regulates oligodendrocyte (OL) differentiation and myelin gene expression in other models. Therefore, we investigated p38MAPK signaling pathways. We used primary rat neural progenitor cells (NPCs) and a mouse oligodendrocyte progenitor cell (OPC) line (N20.1 cells) to investigate the molecular mechanisms of Tβ4-enhanced oligodendrogenesis. NPCs were isolated from rat subventricular zone (SVZ) of the lateral ventricles (n=12). Primary NPCs and N20.1 cells were grown in the presence of 0, 25 and 50 ng/ml of Tβ4 (RegeneRx Biopharmaceuticals Inc, Rockville, MD) for 14 days. Quantitative real-time PCR and Western blot data showed significant induction of both expression and phosphorylation of p38MAPK with simultaneous inhibition of phosphorylation of extracellular signal regulated kinase (ERK1), c-Jun N-terminal kinase 1 (JNK1), leading to reduction of phosphorylation of c-Jun, a potent negative regulator of transcription of myelin genes. These effects were reversed with transfection of Tβ4siRNA. Our data indicate that Tβ4 treatment induces OL differentiation by inducing p38MAPK with parallel inactivation of ERK1 and JNK1, thus preventing the accumulation of phosphorylated c-Jun. PMID:23073962

  18. Gestational nicotine exposure modifies myelin gene expression in the brains of adolescent rats with sex differences

    PubMed Central

    Cao, J; Wang, J; Dwyer, J B; Gautier, N M; Wang, S; Leslie, F M; Li, M D

    2013-01-01

    Myelination defects in the central nervous system (CNS) are associated with various psychiatric disorders, including drug addiction. As these disorders are often observed in individuals prenatally exposed to cigarette smoking, we tested the hypothesis that such exposure impairs central myelination in adolescence, an important period of brain development and the peak age of onset of psychiatric disorders. Pregnant Sprague Dawley rats were treated with nicotine (3 mg kg−1 per day; gestational nicotine (GN)) or gestational saline via osmotic mini pumps from gestational days 4–18. Both male and female offsprings were killed on postnatal day 35 or 36, and three limbic brain regions, the prefrontal cortex (PFC), caudate putamen and nucleus accumbens, were removed for measurement of gene expression and determination of morphological changes using quantitative real-time PCR (qRT-PCR) array, western blotting and immunohistochemical staining. GN altered myelin gene expression at both the mRNA and protein levels, with striking sex differences. Aberrant expression of myelin-related transcription and trophic factors was seen in GN animals, which correlated highly with the alterations in the myelin gene expression. These correlations suggest that these factors contribute to GN-induced alterations in myelin gene expression and also indicate abnormal function of oligodendrocytes (OLGs), the myelin-producing cells in the CNS. It is unlikely that these changes are attributable solely to an alteration in the number of OLGs, as the cell number was changed only in the PFC of GN males. Together, our findings suggest that abnormal brain myelination underlies various psychiatric disorders and drug abuse associated with prenatal exposure to cigarette smoke. PMID:23591971

  19. Gestational nicotine exposure modifies myelin gene expression in the brains of adolescent rats with sex differences.

    PubMed

    Cao, J; Wang, J; Dwyer, J B; Gautier, N M; Wang, S; Leslie, F M; Li, M D

    2013-01-01

    Myelination defects in the central nervous system (CNS) are associated with various psychiatric disorders, including drug addiction. As these disorders are often observed in individuals prenatally exposed to cigarette smoking, we tested the hypothesis that such exposure impairs central myelination in adolescence, an important period of brain development and the peak age of onset of psychiatric disorders. Pregnant Sprague Dawley rats were treated with nicotine (3 mg kg(-1) per day; gestational nicotine (GN)) or gestational saline via osmotic mini pumps from gestational days 4-18. Both male and female offsprings were killed on postnatal day 35 or 36, and three limbic brain regions, the prefrontal cortex (PFC), caudate putamen and nucleus accumbens, were removed for measurement of gene expression and determination of morphological changes using quantitative real-time PCR (qRT-PCR) array, western blotting and immunohistochemical staining. GN altered myelin gene expression at both the mRNA and protein levels, with striking sex differences. Aberrant expression of myelin-related transcription and trophic factors was seen in GN animals, which correlated highly with the alterations in the myelin gene expression. These correlations suggest that these factors contribute to GN-induced alterations in myelin gene expression and also indicate abnormal function of oligodendrocytes (OLGs), the myelin-producing cells in the CNS. It is unlikely that these changes are attributable solely to an alteration in the number of OLGs, as the cell number was changed only in the PFC of GN males. Together, our findings suggest that abnormal brain myelination underlies various psychiatric disorders and drug abuse associated with prenatal exposure to cigarette smoke. PMID:23591971

  20. Characterization of cultured rat oligodendrocytes proliferating in a serum-free, chemically defined medium.

    PubMed Central

    Saneto, R P; de Vellis, J

    1985-01-01

    A serumless, chemically defined medium has been developed for the culture of oligodendrocytes isolated from primary neonatal rat cerebral cultures. Combined together, insulin, transferrin, and fibroblast growth factor synergistically induced an essentially homogenous population (95-98%) of cells expressing glycerol-3-phosphate dehydrogenase (EC 1.1.1.8) activity to undergo cell division. Proliferating cels were characterized by several criteria: (i) ultrastructural analysis by transmission electron microscopy identified the cell type as an oligodendrocyte; (ii) biochemical assays showed expression of three oligodendrocyte biochemical markers, induction of both glycerol phosphate dehydrogenase and lactate dehydrogenase (EC 1.1.1.27), and presence of 2',3'-cyclic nucleotide 3'-phosphodiesterase (EC 3.1.4.37); and (iii) immunocytochemical staining showed cultures to be 95-98% positive for glycerol phosphate dehydrogenase, 90% for myelin basic protein, 60-70% for galactocerebroside, and 70% for A2B5. Few cells (less than 5%) stained positive for glial fibrillary acidic protein, and none were detected positive for fibronectin. Images PMID:2987930

  1. Co-ultramicronized Palmitoylethanolamide/Luteolin Promotes the Maturation of Oligodendrocyte Precursor Cells

    PubMed Central

    Barbierato, Massimo; Facci, Laura; Marinelli, Carla; Zusso, Morena; Argentini, Carla; Skaper, Stephen D.; Giusti, Pietro

    2015-01-01

    Oligodendrocytes have limited ability to repair the damage to themselves or to other nerve cells, as seen in demyelinating diseases like multiple sclerosis. An important strategy may be to replace the lost oligodendrocytes and/or promote the maturation of undifferentiated oligodendrocyte precursor cells (OPCs). Recent studies show that a composite of co-ultramicronized N-palmitoylethanolamine (PEA) and luteolin (co-ultramicronized PEA/luteolin, 10:1 by mass) is efficacious in improving outcome in experimental models of spinal cord and traumatic brain injuries. Here, we examined the ability of co-ultramicronized PEA/luteolin to promote progression of OPCs into a more differentiated phenotype. OPCs derived from newborn rat cortex were placed in culture and treated the following day with 10 μM co-ultramicronized PEA/luteolin. Cells were collected 1, 4 and 8 days later and analyzed for expression of myelin basic protein (MBP). qPCR and Western blot analyses revealed a time-dependent increase in expression of both mRNA for MBP and MBP content, along with an increased expression of genes involved in lipid biogenesis. Ultramicronized PEA or luteolin, either singly or in simple combination, were ineffective. Further, co-ultramicronized PEA/luteolin promoted morphological development of OPCs and total protein content without affecting proliferation. Co-ultramicronized PEA/luteolin may represent a novel pharmacological strategy to promote OPC maturation. PMID:26578323

  2. CXCR4 Signaling Regulates Remyelination by Endogenous Oligodendrocyte Progenitor Cells in a Viral Model of Demyelination

    PubMed Central

    CARBAJAL, KEVIN S.; MIRANDA, JUAN L.; TSUKAMOTO, MICHELLE R.; LANE, THOMAS E.

    2016-01-01

    Following intracranial infection with the neurotropic JHM strain of mouse hepatitis virus (JHMV), susceptible mice will develop widespread myelin destruction that results in pathological and clinical outcomes similar to those seen in humans with the demyelinating disease Multiple Sclerosis (MS). Partial remyelination and clinical recovery occurs during the chronic phase following control of viral replication yet the signaling mechanisms regulating these events remain enigmatic. Here we report the kinetics of proliferation and maturation of oligodendrocyte progenitor cells (OPCs) within the spinal cord following JHMV-induced demyelination and that CXCR4 signaling contributes to the maturation state of OPCs. Following treatment with AMD3100, a specific inhibitor of CXCR4, mice recovering from widespread demyelination exhibit a significant (P < 0.01) increase in the number of OPCs and fewer (P < 0.05) mature oligodendrocytes compared with HBSS-treated animals. These results suggest that CXCR4 signaling is required for OPCs to mature and contribute to remyelination in response to JHMV-induced demyelination. To assess if this effect is reversible and has potential therapeutic benefit, we pulsed mice with AMD3100 and then allowed them to recover. This treatment strategy resulted in increased numbers of mature oligodendrocytes, enhanced remyelination, and improved clinical outcome. These findings highlight the possibility to manipulate OPCs in order to increase the pool of remyelination-competent cells that can participate in recovery. PMID:21830237

  3. 1,25-Dihydroxyvitamin D3 enhances neural stem cell proliferation and oligodendrocyte differentiation.

    PubMed

    Shirazi, Hasti Atashi; Rasouli, Javad; Ciric, Bogoljub; Rostami, Abdolmohamad; Zhang, Guang-Xian

    2015-04-01

    1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) has recently been found to suppress experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Although its effect was attributed to an anti-inflammatory mechanism, it is not clear whether this treatment can also directly act on neural cells to promote CNS recovery. The present study investigates the effect of various concentrations of 1,25(OH)2D3 on neural stem cell (NSC) proliferation and their differentiation to oligodendrocytes, the myelinating cells. We have, for the first time, shown that NSCs constitutively express vitamin D receptor (VDR), which can be upregulated by 1,25(OH)2D3. This vitamin significantly enhanced proliferation of NSCs, and enhanced their differentiation into neurons and oligodendrocytes, but not astrocytes. NSCs treated with 1,25(OH)2D3 showed increased expression of NT-3, BDNF, GDNF and CNTF, important neurotrophic factors for neural cell survival and differentiation. Overall, we demonstrated that 1,25(OH)2D3 has a direct effect on NSC proliferation, survival, and neuron/oligodendrocyte differentiation, thus representing a novel mechanism underlying its remyelinating and neuroprotective effect in MS/EAE therapy. PMID:25681066

  4. Multiple splice isoforms of proteolipid M6B in neurons and oligodendrocytes.

    PubMed

    Werner, H; Dimou, L; Klugmann, M; Pfeiffer, S; Nave, K A

    2001-12-01

    Proteolipids are abundant integral membrane proteins, initially described as structural proteins of CNS myelin. More recently, two neuronal proteins related to proteolipid protein (PLP), termed M6A and M6B, were identified, suggesting a common function of proteolipids in oligodendrocytes and neurons. We have analyzed the X-linked M6B gene and discovered an unexpected complexity of protein isoforms. Two promoters and alternative exons yield at least eight M6B proteins and polypeptides, differentially expressed in neurons and oligodendrocytes. Six isoforms are tetraspan membrane proteins that differ by highly conserved amino- and carboxy-terminal domains, termed alpha, beta, psi, and omega. In MDCK cells, the beta-domain of M6B stabilizes tetraspan proteolipids at the cell surface, whereas non-beta isoforms are more abundant in intracellular compartments. Cotransfection experiments suggest a physical interaction of M6B and mutant PLP, when retained in the endoplasmic reticulum, that may also contribute to oligodendrocyte dysfunction in Pelizaeus-Merzbacher disease. PMID:11749036

  5. Electroacupuncture ameliorates memory impairments by enhancing oligodendrocyte regeneration in a mouse model of prolonged cerebral hypoperfusion

    PubMed Central

    Ahn, Sung Min; Kim, Yu Ri; Kim, Ha Neui; Shin, Yong-Il; Shin, Hwa Kyoung; Choi, Byung Tae

    2016-01-01

    We modeled prolonged cerebral hypoperfusion in mice using bilateral common carotid artery stenosis (BCAS) and electroacupuncture (EA) stimulation was applied at two acupoints, Baihui (GV20) and Dazhui (GV14). In behavioral tests of memory, BCAS produced impairments in spatial and short-term memory in mice that were attenuated by therapeutic EA stimulation. Therapeutic use of EA in BCAS also enhanced oligodendrocyte (OL) differentiation from oligodendrocyte precursor cells (OPCs), in association with white matter improvements in the corpus callosum (CC). In PCR analyses of growth factor gene expression, significant positive changes in 3 genes were observed following EA stimulation in BCAS, and here we highlight alterations in neurotrophin-4/5 (NT4/5). We confirmed EA-mediated positive changes in the expression of NT4/5 and its receptor, tyrosine receptor kinase B (TrkB). Treatment of naïve and BCAS + EA animals with a selective TrkB antagonist, ANA-12, produced losses of myelin and cognitive function that were ameliorated by EA therapy. Moreover, following BCAS we observed an EA-dependent increase in phospho-activated CREB (a downstream mediator of NT4/5-TrkB signaling) in OPCs and OLs of the CC. Our results suggest that EA stimulation promotes the recovery of memory function following white matter injury via a mechanism that promotes oligodendrocyte regeneration and involves NT4/5-TrkB signaling. PMID:27350403

  6. Electroacupuncture ameliorates memory impairments by enhancing oligodendrocyte regeneration in a mouse model of prolonged cerebral hypoperfusion.

    PubMed

    Ahn, Sung Min; Kim, Yu Ri; Kim, Ha Neui; Shin, Yong-Il; Shin, Hwa Kyoung; Choi, Byung Tae

    2016-01-01

    We modeled prolonged cerebral hypoperfusion in mice using bilateral common carotid artery stenosis (BCAS) and electroacupuncture (EA) stimulation was applied at two acupoints, Baihui (GV20) and Dazhui (GV14). In behavioral tests of memory, BCAS produced impairments in spatial and short-term memory in mice that were attenuated by therapeutic EA stimulation. Therapeutic use of EA in BCAS also enhanced oligodendrocyte (OL) differentiation from oligodendrocyte precursor cells (OPCs), in association with white matter improvements in the corpus callosum (CC). In PCR analyses of growth factor gene expression, significant positive changes in 3 genes were observed following EA stimulation in BCAS, and here we highlight alterations in neurotrophin-4/5 (NT4/5). We confirmed EA-mediated positive changes in the expression of NT4/5 and its receptor, tyrosine receptor kinase B (TrkB). Treatment of naïve and BCAS + EA animals with a selective TrkB antagonist, ANA-12, produced losses of myelin and cognitive function that were ameliorated by EA therapy. Moreover, following BCAS we observed an EA-dependent increase in phospho-activated CREB (a downstream mediator of NT4/5-TrkB signaling) in OPCs and OLs of the CC. Our results suggest that EA stimulation promotes the recovery of memory function following white matter injury via a mechanism that promotes oligodendrocyte regeneration and involves NT4/5-TrkB signaling. PMID:27350403

  7. Fibroblast growth factor signalling in multiple sclerosis: inhibition of myelination and induction of pro-inflammatory environment by FGF9.

    PubMed

    Lindner, Maren; Thümmler, Katja; Arthur, Ariel; Brunner, Sarah; Elliott, Christina; McElroy, Daniel; Mohan, Hema; Williams, Anna; Edgar, Julia M; Schuh, Cornelia; Stadelmann, Christine; Barnett, Susan C; Lassmann, Hans; Mücklisch, Steve; Mudaliar, Manikhandan; Schaeren-Wiemers, Nicole; Meinl, Edgar; Linington, Christopher

    2015-07-01

    Remyelination failure plays an important role in the pathophysiology of multiple sclerosis, but the underlying cellular and molecular mechanisms remain poorly understood. We now report actively demyelinating lesions in patients with multiple sclerosis are associated with increased glial expression of fibroblast growth factor 9 (FGF9), which we demonstrate inhibits myelination and remyelination in vitro. This inhibitory activity is associated with the appearance of multi-branched 'pre-myelinating' MBP+ / PLP+ oligodendrocytes that interact with axons but fail to assemble myelin sheaths; an oligodendrocyte phenotype described previously in chronically demyelinated multiple sclerosis lesions. This inhibitory activity is not due to a direct effect of FGF9 on cells of the oligodendrocyte lineage but is mediated by factors secreted by astrocytes. Transcriptional profiling and functional validation studies demonstrate that these include effects dependent on increased expression of tissue inhibitor of metalloproteinase-sensitive proteases, enzymes more commonly associated with extracellular matrix remodelling. Further, we found that FGF9 induces expression of Ccl2 and Ccl7, two pro-inflammatory chemokines that contribute to recruitment of microglia and macrophages into multiple sclerosis lesions. These data indicate glial expression of FGF9 can initiate a complex astrocyte-dependent response that contributes to two distinct pathogenic pathways involved in the development of multiple sclerosis lesions. Namely, induction of a pro-inflammatory environment and failure of remyelination; a combination of effects predicted to exacerbate axonal injury and loss in patients. PMID:25907862

  8. Glycoprotein Analysis

    NASA Astrophysics Data System (ADS)

    Fernandes, Daryl; Spencer, Daniel

    This chapter provides an overview of practical methods for glycosylation analysis of glycoprotein therapeutics . The topics include glycoprofiling methods for glycoforms, monosaccharides (neutral and N-acetylated species as well as sialic acids), oligosaccharides (chemical and enzymatic methods for glycan release, post-release purification, labeling and derivatization, different types of glycan HPLC and MS), and glycosylation site profiling.

  9. Glycoprotein synthesis

    DOEpatents

    Schultz, Peter G.; Wang, Lei; Zhang, Zhiwen

    2006-10-31

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  10. Glycoprotein synthesis

    DOEpatents

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

    2009-07-14

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  11. Glycoprotein synthesis

    DOEpatents

    Schultz, Peter G.; Wang, Lei; Zhang, Zhiwen

    2007-05-15

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  12. Glycoprotein synthesis

    DOEpatents

    Schultz, Peter G.; Wang, Lei; Zhang, Zhiwen

    2005-08-09

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  13. Glycoprotein synthesis

    DOEpatents

    Schultz, Peter G.; Wang, Lei; Zhang, Zhiwen

    2007-08-28

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  14. Glycoprotein synthesis

    DOEpatents

    Schultz, Peter G.; Wang, Lei; Zhang, Zhiwen

    2010-11-02

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  15. Glycoprotein synthesis

    DOEpatents

    Schultz, Peter G.; Wang, Lei; Zhang, Zhiwen

    2007-07-03

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  16. Glycoprotein synthesis

    DOEpatents

    Schultz, Peter G.; Wang, Lei; Zhang, Zhiwen

    2007-02-27

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  17. Glycoprotein synthesis

    DOEpatents

    Schultz, Peter G.; Wang, Lei; Zhang, Zhiwen

    2010-11-16

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  18. Glycoprotein synthesis

    DOEpatents

    Shultz, Peter G.; Wang, Lei; Zhang, Zhiwen

    2007-04-03

    Methods for making glycoproteins, both in vitro and in vivo, are provided. One method involves incorporating an unnatural amino acid into a protein and attaching one or more saccharide moieties to the unnatural amino acid. Another method involves incorporating an unnatural amino acid that includes a saccharide moiety into a protein. Proteins made by both methods can be further modified with additional sugars.

  19. Contact-Mediated Inhibition Between Oligodendrocyte Progenitor Cells and Motor Exit Point Glia Establishes the Spinal Cord Transition Zone

    PubMed Central

    Smith, Cody J.; Morris, Angela D.; Welsh, Taylor G.; Kucenas, Sarah

    2014-01-01

    Rapid conduction of action potentials along motor axons requires that oligodendrocytes and Schwann cells myelinate distinct central and peripheral nervous system (CNS and PNS) domains along the same axon. Despite the importance of this arrangement for nervous system function, the mechanisms that establish and maintain this precise glial segregation at the motor exit point (MEP) transition zone are unknown. Using in vivo time-lapse imaging in zebrafish, we observed that prior to myelination, oligodendrocyte progenitor cells (OPCs) extend processes into the periphery via the MEP and immediately upon contact with spinal motor root glia retract back into the spinal cord. Characterization of the peripheral cell responsible for repelling OPC processes revealed that it was a novel, CNS-derived population of glia we propose calling MEP glia. Ablation of MEP glia resulted in the absence of myelinating glia along spinal motor root axons and an immediate breach of the MEP by OPCs. Taken together, our results identify a novel population of CNS-derived peripheral glia located at the MEP that selectively restrict the migration of OPCs into the periphery via contact-mediated inhibition. PMID:25268888

  20. Acceleration of conduction velocity linked to clustering of nodal components precedes myelination

    PubMed Central

    Freeman, Sean A.; Desmazières, Anne; Simonnet, Jean; Gatta, Marie; Pfeiffer, Friederike; Aigrot, Marie Stéphane; Rappeneau, Quentin; Guerreiro, Serge; Michel, Patrick Pierre; Yanagawa, Yuchio; Barbin, Gilles; Brophy, Peter J.; Fricker, Desdemona; Lubetzki, Catherine; Sol-Foulon, Nathalie

    2015-01-01

    High-density accumulation of voltage-gated sodium (Nav) channels at nodes of Ranvier ensures rapid saltatory conduction along myelinated axons. To gain insight into mechanisms of node assembly in the CNS, we focused on early steps of nodal protein clustering. We show in hippocampal cultures that prenodes (i.e., clusters of Nav channels colocalizing with the scaffold protein ankyrinG and nodal cell adhesion molecules) are detected before myelin deposition along axons. These clusters can be induced on purified neurons by addition of oligodendroglial-secreted factor(s), whereas ankyrinG silencing prevents their formation. The Nav isoforms Nav1.1, Nav1.2, and Nav1.6 are detected at prenodes, with Nav1.6 progressively replacing Nav1.2 over time in hippocampal neurons cultured with oligodendrocytes and astrocytes. However, the oligodendrocyte-secreted factor(s) can induce the clustering of Nav1.1 and Nav1.2 but not of Nav1.6 on purified neurons. We observed that prenodes are restricted to GABAergic neurons, whereas clustering of nodal proteins only occurs concomitantly with myelin ensheathment on pyramidal neurons, implying separate mechanisms of assembly among different neuronal subpopulations. To address the functional significance of these early clusters, we used single-axon electrophysiological recordings in vitro and showed that prenode formation is sufficient to accelerate the speed of axonal conduction before myelination. Finally, we provide evidence that prenodal clusters are also detected in vivo before myelination, further strengthening their physiological relevance. PMID:25561543

  1. Acceleration of conduction velocity linked to clustering of nodal components precedes myelination.

    PubMed

    Freeman, Sean A; Desmazières, Anne; Simonnet, Jean; Gatta, Marie; Pfeiffer, Friederike; Aigrot, Marie Stéphane; Rappeneau, Quentin; Guerreiro, Serge; Michel, Patrick Pierre; Yanagawa, Yuchio; Barbin, Gilles; Brophy, Peter J; Fricker, Desdemona; Lubetzki, Catherine; Sol-Foulon, Nathalie

    2015-01-20

    High-density accumulation of voltage-gated sodium (Nav) channels at nodes of Ranvier ensures rapid saltatory conduction along myelinated axons. To gain insight into mechanisms of node assembly in the CNS, we focused on early steps of nodal protein clustering. We show in hippocampal cultures that prenodes (i.e., clusters of Nav channels colocalizing with the scaffold protein ankyrinG and nodal cell adhesion molecules) are detected before myelin deposition along axons. These clusters can be induced on purified neurons by addition of oligodendroglial-secreted factor(s), whereas ankyrinG silencing prevents their formation. The Nav isoforms Nav1.1, Nav1.2, and Nav1.6 are detected at prenodes, with Nav1.6 progressively replacing Nav1.2 over time in hippocampal neurons cultured with oligodendrocytes and astrocytes. However, the oligodendrocyte-secreted factor(s) can induce the clustering of Nav1.1 and Nav1.2 but not of Nav1.6 on purified neurons. We observed that prenodes are restricted to GABAergic neurons, whereas clustering of nodal proteins only occurs concomitantly with myelin ensheathment on pyramidal neurons, implying separate mechanisms of assembly among different neuronal subpopulations. To address the functional significance of these early clusters, we used single-axon electrophysiological recordings in vitro and showed that prenode formation is sufficient to accelerate the speed of axonal conduction before myelination. Finally, we provide evidence that prenodal clusters are also detected in vivo before myelination, further strengthening their physiological relevance. PMID:25561543

  2. Myelin repair is accelerated by inactivating CXCR2 on non-hematopoietic cells

    PubMed Central

    Liu, LiPing; Darnall, Lindsey; Hu, Taofang; Choi, Karen; Ransohoff, Richard M.

    2010-01-01

    Multiple Sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) and remyelination in MS ultimately fails. Although strategies to promote myelin repair are eagerly sought, mechanisms underlying remyelination in vivo have been elusive. CXCR2 is expressed on neutrophils and oligodendrocyte lineage cells in the central nervous system (CNS). CXCR2 positive neutrophils facilitate inflammatory demyelination in demyelination models such as experimental autoimmune encephalomyelitis (EAE) and cuprizone intoxication. Systemic injection of a small molecule CXCR2 antagonist at the onset of EAE decreased demyelinated lesions. These results left the cellular target of the CXCR2 antagonist uncertain, and did not clarify whether CXCR2 blockade prevented demyelination or promoted remyelination. Here, we show that the actions of CXCR2 on non-hematopoietic cells unexpectedly delay myelin repair. Bone marrow chimeric mice (Cxcr2+/−→Cxcr2−/− and Cxcr2+/−→Cxcr2+/+) were subjected to two distinct models of myelin injury. In all cases, myelin repair was more efficient in Cxcr2+/−→Cxcr2−/− animals. Oligodendrocyte progenitor cells (OPCs) in demyelinated lesions of Cxcr2+/−→Cxcr2−/− mice proliferated earlier and more vigorously than in tissues from Cxcr2+/−→Cxcr2+/+ animals. In vitro demyelinated CNS slice cultures also showed better myelin repair when CXCR2 was blocked with neutralizing antibodies, or was genetically deleted. Our results suggest that CXCR2 inactivation permits optimal spatiotemporal positioning of OPCs in demyelinating lesions to receive local proliferative and differentiating signals. Given that CXCR2 exerts dual functions which promote demyelination and decrease remyelination by actions towards hematopoietic cells and non-hematopoietic cells respectively, our findings identify CXCR2 as a promising drug target for clinical demyelinating disorders. PMID:20610741

  3. Actin filament turnover drives leading edge growth during myelin sheath formation in the central nervous system

    PubMed Central

    Schmitt, Sebastian; Snaidero, Nicolas; Mitkovski, Mišo; Velte, Caroline; Brückner, Bastian R.; Alexopoulos, Ioannis; Czopka, Tim; Jung, Sang Y.; Rhee, Jeong S.; Janshoff, Andreas; Witke, Walter; Schaap, Iwan A.T.; Lyons, David A.; Simons, Mikael

    2016-01-01

    Summary During central nervous system development, oligodendrocytes wrap their plasma membrane around axons to generate multi-lamellar myelin sheaths. To drive growth at the leading edge of myelin at the interface with the axon, mechanical forces are necessary, but the underlying mechanisms are not known. Using an interdisciplinary approach that combines morphological, genetic and biophysical analyses, we identified a key role for actin filament network turnover in myelin growth. At the onset of myelin biogenesis, F-actin is redistributed to the leading edge, where its polymerization-based forces push out non-adhesive and motile protrusions. F-actin disassembly converts protrusions into sheets by reducing surface tension and in turn inducing membrane spreading and adhesion. We identified the actin depolymerizing factor ADF/Cofilin1, which mediates high F-actin turnover rates, as essential factor in this process. We propose that F-actin turnover is the driving force in myelin wrapping by regulating repetitive cycles of leading edge protrusion and spreading. PMID:26166299

  4. The Transcriptional Activator Krüppel-like Factor-6 Is Required for CNS Myelination

    PubMed Central

    Mariani, John N.; Zhang, Jingya; Liu, Jia; Sawai, Setsu; Chapouly, Candice; Horng, Sam; Kramer, Elisabeth G.; Loo, Hannah; Burlant, Natalie; Nudelman, German; Lee, Young-Min; Braun, David A.; Lu, Q. Richard; Narla, Goutham; Raine, Cedric S.; Friedman, Scott L.; Casaccia, Patrizia; John, Gareth R.

    2016-01-01

    Growth factors of the gp130 family promote oligodendrocyte differentiation, and viability, and myelination, but their mechanisms of action are incompletely understood. Here, we show that these effects are coordinated, in part, by the transcriptional activator Krüppel-like factor-6 (Klf6). Klf6 is rapidly induced in oligodendrocyte progenitors (OLP) by gp130 factors, and promotes differentiation. Conversely, in mice with lineage-selective Klf6 inactivation, OLP undergo maturation arrest followed by apoptosis, and CNS myelination fails. Overlapping transcriptional and chromatin occupancy analyses place Klf6 at the nexus of a novel gp130-Klf-importin axis, which promotes differentiation and viability in part via control of nuclear trafficking. Klf6 acts as a gp130-sensitive transactivator of the nuclear import factor importin-α5 (Impα5), and interfering with this mechanism interrupts step-wise differentiation. Underscoring the significance of this axis in vivo, mice with conditional inactivation of gp130 signaling display defective Klf6 and Impα5 expression, OLP maturation arrest and apoptosis, and failure of CNS myelination. PMID:27213272

  5. Salvianolic acid B protects the myelin sheath around injured spinal cord axons.

    PubMed

    Zhu, Zhe; Ding, Lu; Qiu, Wen-Feng; Wu, Hong-Fu; Li, Rui

    2016-03-01

    Salvianolic acid B, an active pharmaceutical compound present in Salvia miltiorrhiza, exerts a neuroprotective effect in animal models of brain and spinal cord injury. Salvianolic acid B can promote recovery of neurological function; however, its protective effect on the myelin sheath after spinal cord injury remains poorly understood. Thus, in this study, in vitro tests showed that salvianolic acid B contributed to oligodendrocyte precursor cell differentiation, and the most effective dose was 20 μg/mL. For in vivo investigation, rats with spinal cord injury were intraperitoneally injected with 20 mg/kg salvianolic acid B for 8 weeks. The amount of myelin sheath and the number of regenerating axons increased, neurological function recovered, and caspase-3 expression was decreased in the spinal cord of salvianolic acid B-treated animals compared with untreated control rats. These results indicate that salvianolic acid B can protect axons and the myelin sheath, and can promote the recovery of neurological function. Its mechanism of action is likely to be associated with inhibiting apoptosis and promoting the differentiation and maturation of oligodendrocyte precursor cells. PMID:27127491

  6. Intracellular Protein Shuttling: A Mechanism Relevant for Myelin Repair in Multiple Sclerosis?

    PubMed

    Göttle, Peter; Küry, Patrick

    2015-01-01

    A prominent feature of demyelinating diseases such as multiple sclerosis (MS) is the degeneration and loss of previously established functional myelin sheaths, which results in impaired signal propagation and axonal damage. However, at least in early disease stages, partial replacement of lost oligodendrocytes and thus remyelination occur as a result of resident oligodendroglial precursor cell (OPC) activation. These cells represent a widespread cell population within the adult central nervous system (CNS) that can differentiate into functional myelinating glial cells to restore axonal functions. Nevertheless, the spontaneous remyelination capacity in the adult CNS is inefficient because OPCs often fail to generate new oligodendrocytes due to the lack of stimulatory cues and the presence of inhibitory factors. Recent studies have provided evidence that regulated intracellular protein shuttling is functionally involved in oligodendroglial differentiation and remyelination activities. In this review we shed light on the role of the subcellular localization of differentiation-associated factors within oligodendroglial cells and show that regulation of intracellular localization of regulatory factors represents a crucial process to modulate oligodendroglial maturation and myelin repair in the CNS. PMID:26151843

  7. The Transcriptional Activator Krüppel-like Factor-6 Is Required for CNS Myelination.

    PubMed

    Laitman, Benjamin M; Asp, Linnéa; Mariani, John N; Zhang, Jingya; Liu, Jia; Sawai, Setsu; Chapouly, Candice; Horng, Sam; Kramer, Elisabeth G; Mitiku, Nesanet; Loo, Hannah; Burlant, Natalie; Pedre, Xiomara; Hara, Yuko; Nudelman, German; Zaslavsky, Elena; Lee, Young-Min; Braun, David A; Lu, Q Richard; Narla, Goutham; Raine, Cedric S; Friedman, Scott L; Casaccia, Patrizia; John, Gareth R

    2016-05-01

    Growth factors of the gp130 family promote oligodendrocyte differentiation, and viability, and myelination, but their mechanisms of action are incompletely understood. Here, we show that these effects are coordinated, in part, by the transcriptional activator Krüppel-like factor-6 (Klf6). Klf6 is rapidly induced in oligodendrocyte progenitors (OLP) by gp130 factors, and promotes differentiation. Conversely, in mice with lineage-selective Klf6 inactivation, OLP undergo maturation arrest followed by apoptosis, and CNS myelination fails. Overlapping transcriptional and chromatin occupancy analyses place Klf6 at the nexus of a novel gp130-Klf-importin axis, which promotes differentiation and viability in part via control of nuclear trafficking. Klf6 acts as a gp130-sensitive transactivator of the nuclear import factor importin-α5 (Impα5), and interfering with this mechanism interrupts step-wise differentiation. Underscoring the significance of this axis in vivo, mice with conditional inactivation of gp130 signaling display defective Klf6 and Impα5 expression, OLP maturation arrest and apoptosis, and failure of CNS myelination. PMID:27213272

  8. Salvianolic acid B protects the myelin sheath around injured spinal cord axons

    PubMed Central

    Zhu, Zhe; Ding, Lu; Qiu, Wen-feng; Wu, Hong-fu; Li, Rui

    2016-01-01

    Salvianolic acid B, an active pharmaceutical compound present in Salvia miltiorrhiza, exerts a neuroprotective effect in animal models of brain and spinal cord injury. Salvianolic acid B can promote recovery of neurological function; however, its protective effect on the myelin sheath after spinal cord injury remains poorly understood. Thus, in this study, in vitro tests showed that salvianolic acid B contributed to oligodendrocyte precursor cell differentiation, and the most effective dose was 20 μg/mL. For in vivo investigation, rats with spinal cord injury were intraperitoneally injected with 20 mg/kg salvianolic acid B for 8 weeks. The amount of myelin sheath and the number of regenerating axons increased, neurological function recovered, and caspase-3 expression was decreased in the spinal cord of salvianolic acid B-treated animals compared with untreated control rats. These results indicate that salvianolic acid B can protect axons and the myelin sheath, and can promote the recovery of neurological function. Its mechanism of action is likely to be associated with inhibiting apoptosis and promoting the differentiation and maturation of oligodendrocyte precursor cells. PMID:27127491

  9. Myelination-related genes are associated with decreased white matter integrity in schizophrenia.

    PubMed

    Chavarria-Siles, Ivan; White, Tonya; de Leeuw, Christiaan; Goudriaan, Andrea; Lips, Esther; Ehrlich, Stefan; Turner, Jessica A; Calhoun, Vince D; Gollub, Randy L; Magnotta, Vincent A; Ho, Beng-Choon; Smit, August B; Verheijen, Mark H G; Posthuma, Danielle

    2016-03-01

    Disruptions in white matter (WM) tract structures have been implicated consistently in the pathophysiology of schizophrenia. Global WM integrity--as measured by fractional anisotropy (FA)--is highly heritable and may provide a good endophenotype for genetic studies of schizophrenia. WM abnormalities in schizophrenia are not localized to one specific brain region but instead reflect global low-level decreases in FA coupled with focal abnormalities. In this study, we sought to investigate whether functional gene sets associated with schizophrenia are also associated with WM integrity. We analyzed FA and genetic data from the Mind Research Network Clinical Imaging Consortium to study the effect of multiple oligodendrocyte gene sets on schizophrenia and WM integrity using a functional gene set analysis in 77 subjects with schizophrenia and 104 healthy controls. We found that a gene set involved in myelination was significantly associated with schizophrenia and FA. This gene set includes 17 genes that are expressed in oligodendrocytes and one neuronal gene (NRG1) that is known to regulate myelination. None of the genes within the gene set were associated with schizophrenia or FA individually, suggesting that no single gene was driving the association of the gene set. Our findings support the hypothesis that multiple genetic variants in myelination-related genes contribute to the observed correlation between schizophrenia and decreased WM integrity as measured by FA. PMID:26014434

  10. Up-Regulation of Oligodendrocyte Lineage Markers in the Cerebellum of Autistic Patients: Evidence from Network Analysis of Gene Expression.

    PubMed

    Zeidán-Chuliá, Fares; de Oliveira, Ben-Hur Neves; Casanova, Manuel F; Casanova, Emily L; Noda, Mami; Salmina, Alla B; Verkhratsky, Alexei

    2016-08-01

    Autism is a neurodevelopmental disorder manifested by impaired social interaction, deficits in communication skills, restricted interests, and repetitive behaviors. In neurodevelopmental, neurodegenerative, and psychiatric disorders, glial cells undergo morphological, biochemical, and functional rearrangements, which are critical for neuronal development, neurotransmission, and synaptic connectivity. Cerebellar function is not limited to motor coordination but also contributes to cognition and may be affected in autism. Oligodendrocytes and specifically oligodendroglial precursors are highly susceptible to oxidative stress and excitotoxic insult. In the present study, we searched for evidence for developmental oligodendropathy in the context of autism by performing a network analysis of gene expression of cerebellar tissue. We created an in silico network model (OLIGO) showing the landscape of interactions between oligodendrocyte markers and demonstrated that more than 50 % (16 out of 30) of the genes within this model displayed significant changes of expression (corrected p value <0.05) in the cerebellum of autistic patients. In particular, we found up-regulation of OLIG2-, MBP-, OLIG1-, and MAG-specific oligodendrocyte markers. We postulate that aberrant expression of oligodendrocyte-specific genes, potentially related to changes in oligodendrogenesis, may contribute to abnormal cerebellar development, impaired myelination, and anomalous synaptic connectivity in autism spectrum disorders (ASD). PMID:26189831

  11. Phylogenetic development of myelin glycosphingolipids.

    PubMed

    Kishimoto, Y

    1986-12-15

    Myelin is a highly specialized membrane, which enwraps axons and facilitates saltatory nerve conduction in vertebrates. Galactocerebroside and its sulfate ester, sulfatide, are highly localized in myelin. To understand the role played by these galactosphingolipids we investigated the changes of these myelin-specific compounds during the course of the evolution of myelin. We found that urodele nerve myelin lacks alpha-hydroxy fatty acid-containing galactosphingolipids. Our morphological and physiological studies of urodele nerves indicated that these hydroxy fatty acid-containing galactosphingolipids probably contribute to fast nerve conduction. Also it is suspected that they are involved in the regulation of the thickness of myelin in relation to the size of the axon. In another study, we discovered that glucocerebroside, which has glucose instead of galactose as its carbohydrate component, is abundantly present in the myelin-like sheath membrane of crustacean nerves. Subsequently, the phylogenetic study indicated that galactocerebrosides were limited to the nervous system of deuterostomes, while all protostome nerves contain glucocerebrosides. The role of glucocerebrosides in multilayered membranes and in the conduction velocity of the protostome nervous system is discussed. PMID:3549016

  12. DTI and Myelin Plasticity in Bipolar Disorder: Integrating Neuroimaging and Neuropathological Findings

    PubMed Central

    Bellani, Marcella; Boschello, Filippo; Delvecchio, Giuseppe; Dusi, Nicola; Altamura, Carlo Alfredo; Ruggeri, Mirella; Brambilla, Paolo

    2016-01-01

    Bipolar disorder (BD) is a major psychiatric illness with a chronic recurrent course, ranked among the worldwide leading disabling diseases. Its pathophysiology is still not completely understood and findings are still inconclusive, though a great interest on the topic has been constantly raised by magnetic resonance imaging, genetic and neuropathological studies. In recent years, diffusion tensor imaging (DTI) investigations have prompted interest in the key role of white matter (WM) abnormalities in BD. In this report, we summarize and comment recent findings from DTI studies in BD, reporting fractional anisotropy as putative measure of WM integrity, as well as recent data from neuropathological studies focusing on oligodendrocyte involvement in WM alterations in BD. DTI research indicates that BD is most commonly associated with a WM disruption within the fronto-limbic network, which may be accompanied by other WM changes spread throughout temporal and parietal regions. Neuropathological studies, mainly focused on the fronto-limbic network, have repeatedly shown a loss in cortical and subcortical oligodendrocyte cell count, although an increased subcortical oligodendrocyte density has been also documented suggesting a putative role in remyelination processes for oligodendrocytes in BD. According to our review, a greater integration between DTI and morphological findings is needed in order to elucidate processes affecting WM, either glial loss or myelin plasticity, on the basis of a more targeted research in BD. PMID:26973545

  13. In vitro analysis of the oligodendrocyte lineage in mice during demyelination and remyelination

    SciTech Connect

    Armstrong, R.; Friedrich, V.L. Jr.; Holmes, K.V.; Dubois-Dalcq, M. )

    1990-09-01

    A demyelinating disease induced in C57B1/6N mice by intracranial injection of a coronavirus (murine hepatitis virus strain A59) is followed by functional recovery and efficient CNS myelin repair. To study the biological properties of the cells involved in this repair process, glial cells were isolated and cultured from spinal cords of these young adult mice during demyelination and remyelination. Using three-color immunofluorescence combined with (3H)thymidine autoradiography, we have analyzed the antigenic phenotype and mitotic potential of individual glial cells. We identified oligodendrocytes with an antibody to galactocerebroside, astrocytes with an antibody to glial fibrillary acidic protein, and oligodendrocyte-type 2 astrocyte (O-2A) progenitor cells with the O4 antibody. Cultures from demyelinated tissue differed in several ways from those of age-matched controls: first, the total number of O-2A lineage cells was strikingly increased; second, the O-2A population consisted of a higher proportion of O4-positive astrocytes and cells of mixed oligodendrocyte-astrocyte phenotype; and third, all the cell types within the O-2A lineage showed enhanced proliferation. This proliferation was not further enhanced by adding PDGF, basic fibroblast growth factor (bFGF), or insulin-like growth factor I (IGF-I) to the defined medium. However, bFGF and IGF-I seemed to influence the fate of O-2A lineage cells in cultures of demyelinated tissue. Basic FGF decreased the percentage of cells expressing galactocerebroside. In contrast, IGF-I increased the relative proportion of oligodendrocytes. Thus, O-2A lineage cells from adult mice display greater phenotypic plasticity and enhanced mitotic potential in response to an episode of demyelination. These properties may be linked to the efficient remyelination achieved in this demyelinating disease.

  14. Abnormal Junctions and Permeability of Myelin in PMP22-Deficient Nerves

    PubMed Central

    Guo, Jiasong; Wang, Leiming; Zhang, Yang; Wu, Jiawen; Arpag, Sezgi; Hu, Bo; Imhof, Beat A.; Tian, Xinxia; Carter, Bruce D.; Suter, Ueli; Li, Jun

    2014-01-01

    Objective The peripheral myelin protein-22 (PMP22) gene is associated with the most common types of inherited neuropathies, including hereditary neuropathy with liability to pressure palsies (HNPP) caused by PMP22 deficiency. However, the function of PMP22 has yet to be defined. Our previous study has shown that PMP22 deficiency causes an impaired propagation of nerve action potentials in the absence of demyelination. In the present study, we tested an alternative mechanism relating to myelin permeability. Methods Utilizing Pmp22+/− mice as a model of HNPP, we evaluated myelin junctions and their permeability using morphological, electrophysiological, and biochemical approaches. Results We show disruption of multiple types of cell junction complexes in peripheral nerve, resulting in increased permeability of myelin and impaired action potential propagation. We further demonstrate that PMP22 interacts with immunoglobulin domain–containing proteins known to regulate tight/adherens junctions and/or transmembrane adhesions, including junctional adhesion molecule-C (JAM-C) and myelin-associated glycoprotein (MAG). Deletion of Jam-c or Mag in mice recapitulates pathology in HNPP. Interpretation Our study reveals a novel mechanism by which PMP22 deficiency affects nerve conduction not through removal of myelin, but through disruption of myelin junctions. PMID:24339129

  15. Topographic Cue from Electrospun Scaffolds Regulate Myelin-Related Gene Expressions in Schwann Cells.

    PubMed

    Radhakrishnan, Janani; Kuppuswamy, Ashok Ayyappa; Sethuraman, Swaminathan; Subramanian, Anuradha

    2015-03-01

    Matured Schwann cells play a vital role in promoting regeneration and restoration of functional peripheral nervous tissue. In the present study, two dimensional film, three dimensional random and longitudinally aligned electrospun fibers of poly(lactide-co-glycolide) were used to evaluate the effect of topography on expressions of myelin related genes. The aligned nanofibrous scaffold demonstrated significant increase in Schwann cell adhesion using after 3, 6 and 12 hours of culture compared to the film and random fibers. Cell morphology, degree of orientation and elongation factor evaluated using a scanning electron microscope revealed that cells on aligned scaffold have spindle morphology, whereas cells on random and two dimensional films favor spherical morphology confirming the effect of topography. Significant increase in elongation factor was observed in aligned scaffold as compared to film and random fibers (p < 0.05). The gene expression analysis revealed that aligned scaffold significantly up-regulated the expression of early myelination markers: myelin-associated glycoprotein and myelin protein zero, cell adhesion molecule: neural cadherin, extracellular matrix molecule: neurocan, as well the down-regulation of non-myelinating Schwann cell marker: neural cell adhesion molecule when compared to random and film (p < 0.05). The gene expression patterns of aligned fibers favor myelination of Schwann cells when compared to film and random fibers. Thus, our results demonstrate that the aligned topography of the scaffold promotes maturation of Schwann cells and thereby its myelination to maintain its functionality. PMID:26307833

  16. Heterogeneous nuclear ribonucleoprotein (hnRNP) F is a novel component of oligodendroglial RNA transport granules contributing to regulation of myelin basic protein (MBP) synthesis.

    PubMed

    White, Robin; Gonsior, Constantin; Bauer, Nina M; Krämer-Albers, Eva-Maria; Luhmann, Heiko J; Trotter, Jacqueline

    2012-01-13

    Myelin basic protein (MBP) is a major component of central nervous system (CNS) myelin. The absence of MBP results in the loss of almost all compact myelin in the CNS. MBP mRNA is sorted into RNA granules that are transported to the periphery of oligodendrocytes in a translationally inactive state. A central mediator of this transport process is the trans-acting factor heterogeneous nuclear ribonucleoprotein (hnRNP) A2 that binds to the cis-acting A2-response element in the 3'UTR of MBP mRNA. Recently, we found that activation of the Src family nonreceptor tyrosine kinase Fyn in oligodendrocytes leads to phosphorylation of hnRNP A2 and to increased translation of MBP mRNA. Here, we identify the RNA-binding protein hnRNP F as a novel component of MBP mRNA transport granules. It is associated with hnRNP A2 and MBP mRNA in cytoplasmic granular structures and is involved in post-transcriptional regulation of MBP expression. Fyn kinase activity results in phosphorylation of hnRNP F in the cytoplasm and its release from MBP mRNA and RNA granules. Our results define hnRNP F as a regulatory element of MBP expression in oligodendrocytes and imply an important function of hnRNP F in the control of myelin synthesis. PMID:22128153

  17. Heterogeneous Nuclear Ribonucleoprotein (hnRNP) F Is a Novel Component of Oligodendroglial RNA Transport Granules Contributing to Regulation of Myelin Basic Protein (MBP) Synthesis*

    PubMed Central

    White, Robin; Gonsior, Constantin; Bauer, Nina M.; Krämer-Albers, Eva-Maria; Luhmann, Heiko J.; Trotter, Jacqueline

    2012-01-01

    Myelin basic protein (MBP) is a major component of central nervous system (CNS) myelin. The absence of MBP results in the loss of almost all compact myelin in the CNS. MBP mRNA is sorted into RNA granules that are transported to the periphery of oligodendrocytes in a translationally inactive state. A central mediator of this transport process is the trans-acting factor heterogeneous nuclear ribonucleoprotein (hnRNP) A2 that binds to the cis-acting A2-response element in the 3′UTR of MBP mRNA. Recently, we found that activation of the Src family nonreceptor tyrosine kinase Fyn in oligodendrocytes leads to phosphorylation of hnRNP A2 and to increased translation of MBP mRNA. Here, we identify the RNA-binding protein hnRNP F as a novel component of MBP mRNA transport granules. It is associated with hnRNP A2 and MBP mRNA in cytoplasmic granular structures and is involved in post-transcriptional regulation of MBP expression. Fyn kinase activity results in phosphorylation of hnRNP F in the cytoplasm and its release from MBP mRNA and RNA granules. Our results define hnRNP F as a regulatory element of MBP expression in oligodendrocytes and imply an important function of hnRNP F in the control of myelin synthesis. PMID:22128153

  18. The good, the bad and the ugly. Macrophages/microglia with a focus on myelin repair.

    PubMed

    Doring, Axinia; Yong, Voon Wee

    2011-01-01

    A feature of most neurological disorders is demyelination, whereby myelin is lost from axons partly through stripping by macrophages/microglia. Spontaneous remyelination by oligodendrocytes that mature from oligodendrocyte precursor cells occurs following demyelination, even in the chronic inflammatory disorder of the central nervous system, multiple sclerosis. If remyelination does not occur or is prevented, then one consequence besides the loss of saltatory nerve conduction is the degeneration of axons. Thus, promoting remyelination is a desired result. In this article, we review the data that despite a reputation as "bad" factors for CNS wellbeing, including the promotion of neuroinflammation and demyelination, some aspects of macrophages/microglia activity are indeed "good", and can engender repair from the "ugly" phenomenon of demyelination. We discuss factors that help promote the benefits of macrophages/microglia activity for remyelination. PMID:21622236

  19. Connexin47 protein phosphorylation and stability in oligodendrocytes depend on expression of Connexin43 protein in astrocytes.

    PubMed

    May, Dennis; Tress, Oliver; Seifert, Gerald; Willecke, Klaus

    2013-05-01

    Panglial networks are essential for normal physiology in the CNS, and the function of distinct connexins participating in these networks is not well understood. We generated Connexin32 (Cx32)-deficient mice with additional deletion of astrocytic Cx43 to explore the role of both connexins in panglial networks. Cx43/Cx32 double knock-out (dKO) mice revealed strong microglial activation in corpus callosum and cingulum along with severe astrogliosis and scar formation. In addition, most of the fine myelinated fibers projecting from the corpus callosum into the cortex were lost. Myelin loss was caused by a strong decrease of oligodendrocytes in the cingulum of Cx43/Cx32dKO mice. Immunoblot analyses using newly generated specific Cx47 antibodies revealed that oligodendrocytic Cx47 is phosphorylated in vivo depending on astrocytic Cx43 expression. In Cx43-deficient mice, Cx47 protein levels were strongly decreased, whereas Cx47 mRNA levels were not altered. Using Cx43G138R/Cx30KO mice, we show that Cx47 expression depends on the presence of astrocytic Cx43 protein and that its gap junctional channel function is not necessary for Cx47 stabilization. In consequence, Cx43/Cx32dKO mice additionally lack Cx47 expression and therefore cannot form oligodendrocytic gap junctions, which explains the phenotypic similarities to Cx32/Cx47dKO mice. Our findings provide strong evidence that phosphorylation and stability of oligodendrocytic Cx47 proteins is dependent on astrocytic Cx43 expression. These results further unravel the complexity of panglial networks and show that results of previous studies using astrocytic Cx43-deficient mice have to be reconsidered. PMID:23637189

  20. Classic and Golli Myelin Basic Protein have distinct developmental trajectories in human visual cortex

    PubMed Central

    Siu, Caitlin R.; Balsor, Justin L.; Jones, David G.; Murphy, Kathryn M.

    2015-01-01

    Traditionally, myelin is viewed as insulation around axons, however, more recent studies have shown it also plays an important role in plasticity, axonal metabolism, and neuroimmune signaling. Myelin is a complex multi-protein structure composed of hundreds of proteins, with Myelin Basic Protein (MBP) being the most studied. MBP has two families: Classic-MBP that is necessary for activity driven compaction of myelin around axons, and Golli-MBP that is found in neurons, oligodendrocytes, and T-cells. Furthermore, Golli-MBP has been called a “molecular link” between the nervous and immune systems. In visual cortex specifically, myelin proteins interact with immune processes to affect experience-dependent plasticity. We studied myelin in human visual cortex using Western blotting to quantify Classic- and Golli-MBP expression in post-mortem tissue samples ranging in age from 20 days to 80 years. We found that Classic- and Golli-MBP have different patterns of change across the lifespan. Classic-MBP gradually increases to 42 years and then declines into aging. Golli-MBP has early developmental changes that are coincident with milestones in visual system sensitive period, and gradually increases into aging. There are three stages in the balance between Classic- and Golli-MBP expression, with Golli-MBP dominating early, then shifting to Classic-MBP, and back to Golli-MBP in aging. Also Golli-MBP has a wave of high inter-individual variability during childhood. These results about cortical MBP expression are timely because they compliment recent advances in MRI techniques that produce high resolution maps of cortical myelin in normal and diseased brain. In addition, the unique pattern of Golli-MBP expression across the lifespan suggests that it supports high levels of neuroimmune interaction in cortical development and in aging. PMID:25964736

  1. Staufen Recruitment into Stress Granules Does Not Affect Early mRNA Transport in Oligodendrocytes

    PubMed Central

    Thomas, María G.; Tosar, Leandro J. Martinez; Loschi, Mariela; Pasquini, Juana M.; Correale, Jorge; Kindler, Stefan; Boccaccio, Graciela L.

    2005-01-01

    Staufen is a conserved double-stranded RNA-binding protein required for mRNA localization in Drosophila oocytes and embryos. The mammalian homologues Staufen 1 and Staufen 2 have been implicated in dendritic RNA targeting in neurons. Here we show that in rodent oligodendrocytes, these two proteins are present in two independent sets of RNA granules located at the distal myelinating processes. A third kind of RNA granules lacks Staufen and contains major myelin mRNAs. Myelin Staufen granules associate with microfilaments and microtubules, and their subcellular distribution is affected by polysome-disrupting drugs. Under oxidative stress, both Staufen 1 and Staufen 2 are recruited into stress granules (SGs), which are stress-induced organelles containing transiently silenced messengers. Staufen SGs contain the poly(A)-binding protein (PABP), the RNA-binding proteins HuR and TIAR, and small but not large ribosomal subunits. Staufen recruitment into perinuclear SGs is paralleled by a similar change in the overall localization of polyadenylated RNA. Under the same conditions, the distribution of recently transcribed and exported mRNAs is not affected. Our results indicate that Staufen 1 and Staufen 2 are novel and ubiquitous SG components and suggest that Staufen RNPs are involved in repositioning of most polysomal mRNAs, but not of recently synthesized transcripts, during the stress response. PMID:15525674

  2. Perturbation of myelin basic protein (Mbp) splice variant expression in developing rat cerebellum following perinatal exposure to methylmercury.

    PubMed

    Padhi, Bhaja K; Pelletier, Guillaume

    2012-09-18

    Myelin sheaths surrounding axons are essential for saltatory conduction of nerve impulse in the central nervous system. A major protein constituent of myelin sheaths is produced by the myelin basic protein (Mbp) gene, whose expression in oligodendrocytes is conserved across vertebrates. In rat, five Mbp splice variants resulting from alternative splicing of exons 2, 5 and/or 6 are characterized. We developed a PCR-based strategy to quantify individual Mbp splice variants and characterized a sixth Mbp splice variant lacking only exon 5. This newly identified splice variant is predominantly expressed in developing rat brain and has orthologs in mouse and human. Many neurotoxic chemicals can perturb myelination and Mbp gene expression. Regulation of Mbp gene expression at the post-transcriptional level was assessed following perinatal exposure to neurotoxic methylmercury (2 mg/kg b.w./day). Similar reductions in total and individual Mbp splice variant mRNA levels suggest that methylmercury-induced perturbation in Mbp gene expression occurred as a consequence of decreased oligodendrocyte cell population in absence of a significant impact on its post-transcriptional regulation. PMID:22835759

  3. Synthesis of gangliosides by cultured oligodendrocytes

    SciTech Connect

    Mack, S.R.; Szuchet, S.; Dawson, G.

    1981-01-01

    Gangliosides are enriched in the nervous system compared to other tissues. The synthesis of gangliosides by monolayer cultures of isolated oligodendrocytes has not previously been investigated. Cells were labeled with (3H) galactose at preselected times and gangliosides isolated by phase partition, purified, and identified by chromatography. Cultured oligodendrocytes showed selectivity in their synthesis of gangliosides, which was expressed in the type of ganglioside synthesized as well as in the change of incorporation over time in culture. For the first ten days, there was very little incorporation of (3H) galactose in gangliosides, but this was followed by a stimulation of uptake for GM3, GM1/GD3, and GD1 gangliosides, reaching a maximum after approximately 25-30 days in vitro. There was little incorporation into GM2 or trisialogangliosides throughout the life of the cultures. Since oligodendrocytes synthesize extensive membranes during this period, one may speculate that the de novo-synthesized gangliosides are used for membranes.

  4. The p38α mitogen-activated protein kinase is a key regulator of myelination and remyelination in the CNS.

    PubMed

    Chung, S-H; Biswas, S; Selvaraj, V; Liu, X-B; Sohn, J; Jiang, P; Chen, C; Chmilewsky, F; Marzban, H; Horiuchi, M; Pleasure, D E; Deng, W

    2015-01-01

    The p38α mitogen-activated protein kinase (MAPK) is one of the serine/threonine kinases regulating a variety of biological processes, including cell-type specification, differentiation and migration. Previous in vitro studies using pharmacological inhibitors suggested that p38 MAPK is essential for oligodendrocyte (OL) differentiation and myelination. To investigate the specific roles of p38α MAPK in OL development and myelination in vivo, we generated p38α conditional knockout (CKO) mice under the PLP and nerve/glial antigen 2 (NG2) gene promoters, as these genes are specifically expressed in OL progenitor cells (OPCs). Our data revealed that myelin synthesis was completely inhibited in OLs differentiated from primary OPC cultures derived from the NG2 Cre-p38α CKO mouse brains. Although an in vivo myelination defect was not obvious after gross examination of these mice, electron microscopic analysis showed that the ultrastructure of myelin bundles was severely impaired. Moreover, the onset of myelination in the corpus callosum was delayed in the knockout mice compared with p38α fl/fl control mice. A delay in OL differentiation in the central nervous system was observed with concomitant downregulation in the expression of OPC- and OL-specific genes such as Olig1 and Zfp488 during early postnatal development. OPC proliferation was not affected during this time. These data indicate that p38α is a positive regulator of OL differentiation and myelination. Unexpectedly, we observed an opposite effect of p38α on remyelination in the cuprizone-induced demyelination model. The p38α CKO mice exhibited better remyelination capability compared with p38α fl/fl mice following demyelination. The opposing roles of p38α in myelination and remyelination could be due to a strong anti-inflammatory effect of p38α or a dual reciprocal regulatory action of p38α on myelin formation during development and on remyelination after demyelination. PMID:25950478

  5. Purinergic signaling mediated by P2X7 receptors controls myelination in sciatic nerves.

    PubMed

    Faroni, A; Smith, R J P; Procacci, P; Castelnovo, L F; Puccianti, E; Reid, A J; Magnaghi, V; Verkhratsky, A

    2014-10-01

    Adenosine-5'-triphosphate, the physiological ligand of P2X receptors, is an important factor in peripheral nerve development. P2X7 receptor is expressed in Schwann cells (SCs), but the specific effects of P2X7 purinergic signaling on peripheral nerve development, myelination, and function are largely unknown. In this study, sciatic nerves from P2X7 knockout mice were analyzed for altered expression of myelin-associated proteins and for alterations in nerve morphology. Immunohistochemical analyses revealed that, in the wild-type peripheral nerves, the P2X7 receptor was localized mainly in myelinating SCs, with only a few immunopositive nonmyelinating SCs. Complete absence of P2X7 receptor protein was confirmed in the sciatic nerves of the knockout mice by Western blot and immunohistochemistry. Western blot analysis revealed that expression levels of the myelin proteins protein zero and myelin-associated glycoprotein are reduced in P2X7 knockout nerves. In accordance with the molecular results, transmission electron microscopy analyses revealed that P2X7 knockout nerves possess significantly more unmyelinated axons, contained in a higher number of Remak bundles. The myelinating/nonmyelinating SC ratio was also decreased in knockout mice, and we found a significantly increased number of irregular fibers compared with control nerves. Nevertheless, the myelin thickness in the knockout was unaltered, suggesting a stronger role for P2X7 in determining SC maturation than in myelin formation. In conclusion, we present morphological and molecular evidence of the importance of P2X7 signaling in peripheral nerve maturation and in determining SC commitment to a myelinating phenotype. PMID:24903685

  6. MicroRNA Expression Profiling of Oligodendrocyte Differentiation from Human Embryonic Stem Cells

    PubMed Central

    Letzen, Brian S.; Liu, Cyndi; Thakor, Nitish V.; Gearhart, John D.; All, Angelo H.; Kerr, Candace L.

    2010-01-01

    Background Cells of the oligodendrocyte (OL) lineage play a vital role in the production and maintenance of myelin, a multilamellar membrane which allows for saltatory conduction along axons. These cells may provide immense therapeutic potential for lost sensory and motor function in demyelinating conditions, such as spinal cord injury, multiple sclerosis, and transverse myelitis. However, the molecular mechanisms controlling OL differentiation are largely unknown. MicroRNAs (miRNAs) are considered the “micromanagers” of gene expression with suggestive roles in cellular differentiation and maintenance. Although unique patterns of miRNA expression in various cell lineages have been characterized, this is the first report documenting their expression during oligodendrocyte maturation from human embryonic stem (hES) cells. Here, we performed a global miRNA analysis to reveal and identify characteristic patterns in the multiple stages leading to OL maturation from hES cells including those targeting factors involved in myelin production. Methodology/Principal Findings We isolated cells from 8 stages of OL differentiation. Total RNA was subjected to miRNA profiling and validations preformed using real-time qRT-PCR. A comparison of miRNAs from our cultured OLs and OL progenitors showed significant similarities with published results from equivalent cells found in the rat and mouse central nervous system. Principal component analysis revealed four main clusters of miRNA expression corresponding to early, mid, and late progenitors, and mature OLs. These results were supported by correlation analyses between adjacent stages. Interestingly, the highest differentially-expressed miRNAs demonstrated a similar pattern of expression throughout all stages of differentiation, suggesting that they potentially regulate a common target or set of targets in this process. The predicted targets of these miRNAs include those with known or suspected roles in oligodendrocyte development

  7. Bromodomains: Translating the words of lysine acetylation into myelin injury and repair.

    PubMed

    Ntranos, Achilles; Casaccia, Patrizia

    2016-06-20

    Bromodomains are evolutionarily highly conserved α-helical structural motifs that recognize and bind acetylated lysine residues. Lysine acetylation is being increasingly recognized as a major posttranslational modification involved in diverse cellular processes and protein interactions and its deregulation has been implicated in the pathophysiology of various human diseases, such as multiple sclerosis and cancer. Bromodomain-containing proteins can have a wide variety of functions, ranging from histone acetyltransferase activity and chromatin remodeling to transcriptional mediation and co-activation. The role of bromodomains in translating a deregulated cell acetylome into disease phenotypes was recently unveiled by the development of small molecule bromodomain inhibitors. This breakthrough discovery highlighted bromodomain-containing proteins as key players of inflammatory pathways responsible for myelin injury and also demonstrated their role in several aspects of myelin repair including oligodendrocyte differentiation and axonal regeneration. PMID:26472704

  8. Cyclin-Dependent Kinase 5 Mediates Adult OPC Maturation and Myelin Repair through Modulation of Akt and GsK-3β Signaling

    PubMed Central

    Luo, FuCheng; Burke, Kathryn; Kantor, Christopher

    2014-01-01

    Failure of remyelination in diseases, such as multiple sclerosis (MS), leads to permanent axonal damage and irreversible functional loss. The mechanisms controlling remyelination are currently poorly understood. Recent studies implicate the cyclin-dependent kinase 5 (Cdk5) in regulating oligodendrocyte (OL) development and myelination in CNS. In this study, we show that Cdk5 is also an important regulator of remyelination. Pharmacological inhibition of Cdk5 inhibits repair of lysolecithin lesions. This inhibition is a consequence of Cdk5 disruption in neural cells because remyelination in slice cultures is blocked by Cdk5 inhibitors, whereas specific deletion of Cdk5 in OLs inhibits myelin repair. In CNP-Cre;Cdk5fl/fl conditional knock-out mouse (Cdk5 cKO), myelin repair was delayed significantly in response to focal demyelinating lesions compared with wild-type animals. The lack of myelin repair was reflected in decreased expression of MBP and proteolipid protein and a reduction in the total number of myelinated axons in the lesion. The number of CC1+ cells in the lesion sites was significantly reduced in Cdk5 cKO compared with wild-type animals although the total number of oligodendrocyte lineage cells (Olig2+ cells) was increased, suggesting that Cdk5 loss perturbs the transition of early OL lineage cell into mature OL and subsequent remyelination. The failure of remyelination in Cdk5 cKO animals was associated with a reduction in signaling through the Akt pathway and an enhancement of Gsk-3β signaling pathways. Together, these data suggest that Cdk5 is critical in regulating the transition of adult oligodendrocyte precursor cells to mature OLs that is essential for myelin repair in adult CNS. PMID:25080600

  9. Bispecificity for myelin and neuronal self-antigens is a common feature of CD4 T cells in C57BL/6 mice.

    PubMed

    Lucca, Liliana E; Desbois, Sabine; Ramadan, Abdulraouf; Ben-Nun, Avraham; Eisenstein, Miriam; Carrié, Nadège; Guéry, Jean-Charles; Sette, Alessandro; Nguyen, Phuong; Geiger, Terrence L; Mars, Lennart T; Liblau, Roland S

    2014-10-01

    The recognition of multiple ligands by a single TCR is an intrinsic feature of T cell biology, with important consequences for physiological and pathological processes. Polyspecific T cells targeting distinct self-antigens have been identified in healthy individuals as well as in the context of autoimmunity. We have previously shown that the 2D2 TCR recognizes the myelin oligodendrocyte glycoprotein epitope (MOG)35-55 as well as an epitope within the axonal protein neurofilament medium (NF-M15-35) in H-2(b) mice. In this study, we assess whether this cross-reactivity is a common feature of the MOG35-55-specific T cell response. To this end, we analyzed the CD4 T cell response of MOG35-55-immunized C57BL/6 mice for cross-reactivity with NF-M15-35. Using Ag recall responses, we established that an important proportion of MOG35-55-specific CD4 T cells also responded to NF-M15-35 in all mice tested. To study the clonality of this response, we analyzed 22 MOG35-55-specific T cell hybridomas expressing distinct TCR. Seven hybridomas were found to cross-react with NF-M15-35. Using an alanine scan of NF-M18-30 and an in silico predictive model, we dissected the molecular basis of cross-reactivity between MOG35-55 and NF-M15-35. We established that NF-M F24, R26, and V27 proved important TCR contacts. Strikingly, the identified TCR contacts are conserved within MOG38-50. Our data indicate that due to linear sequence homology, part of the MOG35-55-specific T cell repertoire of all C57BL/6 mice also recognizes NF-M15-35, with potential implications for CNS autoimmunity. PMID:25135834

  10. Nitric oxide plays a key role in myelination in the developing brain.

    PubMed

    Olivier, Paul; Loron, Gauthier; Fontaine, Romain H; Pansiot, Julien; Dalous, Jérémie; Thi, Hoa Pham; Charriaut-Marlangue, Christiane; Thomas, Jean-Léon; Mercier, Jean-Christophe; Gressens, Pierre; Baud, Olivier

    2010-08-01

    Inhaled nitric oxide (iNO) is one of the most promising therapies used in neonates, but there is little information available about its effect on the developing brain. We explored the effects of both iNO and endogenous NO on developing white matter in rodents. Rat or mouse pups and their mothers were placed in a chamber containing 5 to 20 ppm of NO for 7 days after birth. Neonatal exposure to iNO was associated with a transient increase in central nervous system myelination in rats and C57BL/6 mice without any deleterious effects at low doses (5 ppm) or behavioral consequences in adulthood. Exposure to iNO was associated with a proliferative effect on immature oligodendrocytes and a subsequent promaturational effect. The role of endogenous NO in myelination was investigated in animals treated with the nitric oxides synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME) in the neonatal period; this led to protracted myelination defects and subsequent behavioral deficits in adulthood. These effects were reversed by rescuing L-NAME-treated animals with iNO. Thus, we demonstrate considerable effect of both exogenous and endogenous NO on myelination in rodents. These data point to potential new avenues for neuroprotection in human perinatal brain damage. PMID:20613635

  11. Proliferation of Schwann cells induced by axolemmal and myelin membranes

    SciTech Connect

    Dinneen, M..

    1985-01-01

    Purified Schwann Cells were cultured from neonatal rat sciatic nerve using a modification of the method of Brockes. Schwann cells and contaminating fibroblasts were unambiguously identified using fluorescent antibodies of 2'3' cyclic nucleotide 3'-phosphodiesterase and the thy 1.1 antigen respectively. The Schwann cells were quiescent unless challenged with mitogens. They proliferated rapidly in response to the soluble mitogen, cholera toxin, or to membrane fractions from rat CNS or PNS, prepared by the method of DeVries. Mitogenic activity was present in both axolemmal and myelin enriched fractions and promoted a 10-15 fold increase in the rate of /sup 3/H-thymidine uptake. The axolemmal mitogen was sensitive to heat (80/sup 0/C for 10 minutes), trypsin digestion (0.05% x 30 mins) or to treatment with endoglycosidase D, suggesting that it could be a glycoprotein. Fifty percent of the axolemmal mitogenic activity was solubilized in 1% octyl-glucoside. The solubilized material, however, was very unstable and further purification was not possible. The myelin associated mitogenic activity was markedly different. It was resistant to freeze thaw cycles, trypsin digestion of endoglycosidase treatment and the activity was actually enhanced by heating at 100/sup 0/C for two hours. It is proposed that the axolemmal activity is responsible for Schwann cell proliferation during development and that the myelin associated activity promotes Schwann cell proliferation during Wallerian degeneration.

  12. Integrin-linked kinase regulates oligodendrocyte cytoskeleton, growth cone, and adhesion dynamics.

    PubMed

    Michalski, John-Paul; Cummings, Sarah E; O'Meara, Ryan W; Kothary, Rashmi

    2016-02-01

    Integrin-linked kinase (ILK), a focal adhesion protein, brokers the link between cytoskeleton, cell membrane, and extracellular environment. Here, we demonstrate a role for ILK in laminin-2-mediated adhesion in primary murine oligodendrocytes (OLs) - with ILK loss leading to severe defects in process branching and outgrowth. These defects were partially recovered when the ILK-depleted OLs were instead grown on the non-integrin-activating substrate poly-l-lysine. Intriguingly, ILK loss on the neutral poly-l-lysine substrate led to swelling at the tips of OL processes, which we identified as enlarged growth cones. Employing the bloated ILK-depleted growth cones as template, we demonstrate the appearance of distinct cytoskeletal domains within OL growth cones bearing classic neuronal growth cone architecture. Further, microtubule organization was severely perturbed following ILK loss, with centripetal microtubule looping and failure to bundle occurring in a laminin-2-independent manner. Together, our work highlights differences in specific aspects of OL biology as driven by laminin-2-dependent or independent ILK governed mechanisms. We also reinforce the idea of OLs as growth cone bearing cells and describe the neuronal-like cytoskeleton therein. Finally, we demonstrate a role for ILK in OL growth cone maturation through microtubule regulation, the loss of which translates to decreased process length and myelin production capacity. We describe herein how different substrates fundamentally alter the oligodendrocyte's response to loss of integrin-linked kinase (ILK). On laminin-2 (Ln-2), ILK-depleted oligodendrocytes appear stunted and malformed, while on the non-integrin-activating substrate PLL branching and membrane formation are restored. We also reinforce the idea of oligodendrocytes as growth cone-bearing cells, detailing the growth cone's cytoskeletal architecture. Strikingly, loss of ILK on poly-l-lysine leads to growth cone swelling, the structure's size and

  13. TLR3 Agonist Poly-IC Induces IL-33 and Promotes Myelin Repair

    PubMed Central

    Natarajan, Chandramohan; Yao, Song-Yi; Sriram, Subramaniam

    2016-01-01

    Background Impaired remyelination of demyelinated axons is a major cause of neurological disability. In inflammatory demyelinating disease of the central nervous system (CNS), although remyelination does happen, it is often incomplete, resulting in poor clinical recovery. Poly-IC a known TLR3 agonist and IL-33, a cytokine which is induced by poly-IC are known to influence recovery and promote repair in experimental models of CNS demyelination. Methodology and Principal Findings We examined the effect of addition of poly-IC and IL-33 on the differentiation and maturation of oligodendrocyte precursor cells (OPC) cultured in vitro. Both Poly-IC and IL-33 induced transcription of myelin genes and the differentiation of OPC to mature myelin forming cells. Poly-IC induced IL-33 in OPC and addition of IL-33 to in vitro cultures, amplified further, IL-33 expression suggesting an autocrine regulation of IL-33. Poly-IC and IL-33 also induced phosphorylation of p38MAPK, a signaling molecule involved in myelination. Following the induction of gliotoxic injury with lysolecithin to the corpus callosum (CC), treatment of animals with poly-IC resulted in greater recruitment of OPC and increased staining for myelin in areas of demyelination. Also, poly-IC treated animals showed greater expression of IL-33 and higher expression of M2 phenotype macrophages in the CC. Conclusion/Significance Our studies suggest that poly-IC and IL-33 play a role in myelin repair by enhancing expression of myelin genes and are therefore attractive therapeutic agents for use as remyelinating agents in human demyelinating disease. PMID:27022724

  14. Increased levels of myelin basic protein transcripts in virus-induced demyelination.

    PubMed

    Kristensson, K; Holmes, K V; Duchala, C S; Zeller, N K; Lazzarini, R A; Dubois-Dalcq, M

    In multiple sclerosis, a demyelinating disease of young adults, there is a paucity of myelin repair in the central nervous system (CNS) which is necessary for the restoration of fast saltatory conduction in axons. Consequently, this relapsing disease often causes marked disability. In similar diseases of small rodents, however, remyelination can be quite extensive, as in the demyelinating disease caused by the A59 strain of mouse hepatitis virus (MHV-A59), a coronavirus of mice. To investigate when and where oligodendrocytes are first triggered to repair CNS myelin in such disease, we have used a complementary DNA probe specific for one major myelin protein gene, myelin basic protein (MBP), which hybridizes with the four forms of MBP messenger RNA in rodents. Using Northern blot and in situ hybridization techniques, we previously found that MBP mRNA is first detected at about 5 days after birth, peaks at 18 days and progressively decreases to 25% of the peak levels in the adult. We now report that in spinal cord sections of adult animals with active demyelination and inflammatory cells, in situ hybridization reveals a dramatic increase in probe binding to MBP-specific mRNA at 2-3 weeks after virus inoculation and before remyelination can be detected by morphological methods. This increase of MBP-specific mRNA is found at the edge of the demyelinating area and extends into surrounding areas of normal-appearing white matter. Thus, in situ hybridization with myelin-specific probes appears to be a useful method for detecting the timing, intensity and location of myelin protein gene reactivation preceding remyelination. This method could be used to elucidate whether such a reactivation occurs in multiple sclerosis brain tissue. Our results suggest that in mice, glial cells react to a demyelinating process with widespread MBP mRNA synthesis which may be triggered by a diffusible factor released in the demyelinated areas. PMID:2426599

  15. Polarized domains of myelinated axons.

    PubMed

    Salzer, James L

    2003-10-01

    The entire length of myelinated axons is organized into a series of polarized domains that center around nodes of Ranvier. These domains, which are crucial for normal saltatory conduction, consist of distinct multiprotein complexes of cell adhesion molecules, ion channels, and scaffolding molecules; they also differ in their diameter, organelle content, and rates of axonal transport. Juxtacrine signals from myelinating glia direct their sequential assembly. The composition, mechanisms of assembly, and function of these molecular domains will be reviewed. I also discuss similarities of this domain organization to that of polarized epithelia and present emerging evidence that disorders of domain organization and function contribute to the axonopathies of myelin and other neurologic disorders. PMID:14556710

  16. Efficient Generation of Viral and Integration-Free Human Induced Pluripotent Stem Cell-Derived Oligodendrocytes.

    PubMed

    Espinosa-Jeffrey, Araceli; Blanchi, Bruno; Biancotti, Juan Carlos; Kumar, Shalini; Hirose, Megumi; Mandefro, Berhan; Talavera-Adame, Dodanim; Benvenisty, Nissim; de Vellis, Jean

    2016-01-01

    Here we document three highly reproducible protocols: (1) a culture system for the derivation of human oligodendrocytes (OLs) from human induced pluripotent stem cells (hiPS) and their further maturation-our protocol generates viral- and integration-free OLs that efficiently commit and move forward in the OL lineage, recapitulating all the steps known to occur during in vivo development; (2) a method for the isolation, propagation and maintenance of neural stem cells (NSCs); and (3) a protocol for the production, isolation, and maintenance of OLs from perinatal rodent and human brain-derived NSCs. Our unique culture systems rely on a series of chemically defined media, specifically designed and carefully characterized for each developmental stage of OL as they advance from OL progenitors to mature, myelinating cells. We are confident that these protocols bring our field a step closer to efficient autologous cell replacement therapies and disease modeling. © 2016 by John Wiley & Sons, Inc. PMID:27532816

  17. Vitamin D receptor-retinoid X receptor heterodimer signaling regulates oligodendrocyte progenitor cell differentiation.

    PubMed

    de la Fuente, Alerie Guzman; Errea, Oihana; van Wijngaarden, Peter; Gonzalez, Ginez A; Kerninon, Christophe; Jarjour, Andrew A; Lewis, Hilary J; Jones, Clare A; Nait-Oumesmar, Brahim; Zhao, Chao; Huang, Jeffrey K; ffrench-Constant, Charles; Franklin, Robin J M

    2015-12-01

    The mechanisms regulating differentiation of oligodendrocyte (OLG) progenitor cells (OPCs) into mature OLGs are key to understanding myelination and remyelination. Signaling via the retinoid X receptor γ (RXR-γ) has been shown to be a positive regulator of OPC differentiation. However, the nuclear receptor (NR) binding partner of RXR-γ has not been established. In this study we show that RXR-γ binds to several NRs in OPCs and OLGs, one of which is vitamin D receptor (VDR). Using pharmacological and knockdown approaches we show that RXR-VDR signaling induces OPC differentiation and that VDR agonist vitamin D enhances OPC differentiation. We also show expression of VDR in OLG lineage cells in multiple sclerosis. Our data reveal a role for vitamin D in the regenerative component of demyelinating disease and identify a new target for remyelination medicines. PMID:26644513

  18. Oligodendrocyte ablation affects the coordinated interaction between granule and Purkinje neurons during cerebellum development

    SciTech Connect

    Collin, Ludovic; Doretto, Sandrine; Malerba, Monica; Ruat, Martial; Borrelli, Emiliana . E-mail: borrelli@uci.edu

    2007-08-01

    Oligodendrocytes (OLs) are the glial cells of the central nervous system (CNS) classically known to be devoted to the formation of myelin sheaths around most axons of the vertebrate brain. We have addressed the role of these cells during cerebellar development, by ablating OLs in vivo. Previous analyses had indicated that OL ablation during the first six postnatal days results into a striking cerebellar phenotype, whose major features are a strong reduction of granule neurons and aberrant Purkinje cells development. These two cell types are highly interconnected during cerebellar development through the production of molecules that help their proliferation, differentiation and maintenance. In this article, we present data showing that OL ablation has major effects on the physiology of Purkinje (PC) and granule cells (GC). In particular, OL ablation results into a reduction of sonic hedgehog (Shh), Brain Derived Neurotrophic Factor (BDNF), and Reelin (Rln) expression. These results indicate that absence of OLs profoundly alters the normal cerebellar developmental program.

  19. Regulation of oligodendrocyte precursor migration during development, in adulthood and in pathology.

    PubMed

    de Castro, Fernando; Bribián, Ana; Ortega, Maria Cristina

    2013-11-01

    Oligodendrocytes are the myelin-forming cells in the central nervous system (CNS). These cells originate from oligodendrocyte precursor cells (OPCs) during development, and they migrate extensively from oligodendrogliogenic niches along the neural tube to colonise the entire CNS. Like many other such events, this migratory process is precisely regulated by a battery of positional and signalling cues that act via their corresponding receptors and that are expressed dynamically by OPCs. Here, we will review the cellular and molecular basis of this important event during embryonic and postnatal development, and we will discuss the relevance of the substantial number of OPCs existing in the adult CNS. Similarly, we will consider the behaviour of OPCs in normal and pathological conditions, especially in animal models of demyelination and of the demyelinating disease, multiple sclerosis. The spontaneous remyelination observed after damage in demyelinating pathologies has a limited effect. Understanding the cellular and molecular mechanisms underlying the biology of OPCs, particularly adult OPCs, should help in the design of neuroregenerative strategies to combat multiple sclerosis and other demyelinating diseases. PMID:23689590

  20. RNA-sequencing reveals oligodendrocyte and neuronal transcripts in microglia relevant to central nervous system disease

    PubMed Central

    Walker, Jason; Wylie, Todd; Magrini, Vincent; Apicelli, Anthony J.; Griffith, Malachi; Griffith, Obi L.; Kohsaka, Shinichi; Wu, Gregory F.; Brody, David L.; Mardis, Elaine R.; Gutmann, David H.

    2014-01-01

    Expression profiling of distinct central nervous system (CNS) cell populations has been employed to facilitate disease classification and to provide insights into the molecular basis of brain pathology. One important cell type implicated in a wide variety of CNS disease states is the resident brain macrophage (microglia). In these studies, microglia are often isolated from dissociated brain tissue by flow sorting procedures (FACS) or from postnatal glial cultures by mechanic isolation. Given the highly dynamic and state-dependent functions of these cells, the use of FACS or short-term culture methods may not accurately capture the biology of brain microglia. In the current study, we performed RNA-sequencing using Cx3cr1+/GFP labeled microglia isolated from the brainstem of 6-week old mice to compare the transcriptomes of FACS-sorted versus laser-captured (LCM) microglia. While both isolation techniques resulted in a large number of shared (common) transcripts, we identified transcripts unique to FACS-isolated and LCM-captured microglia. In particular, ~50% of these LCM-isolated microglial transcripts represented genes typically associated with neurons and glia. While these transcripts clearly localized to microglia using complementary methods, they were not translated into protein. Following the induction of murine experimental autoimmune encephalomyelitis (EAE), increased oligodendrocyte and neuronal transcripts were detected in microglia, while only the myelin basic protein oligodendrocyte transcript was increased in microglia after traumatic brain injury (TBI). Collectively, these findings have implications for the design and interpretation of microglia transcriptome-based investigations. PMID:25258010

  1. Antioxidant Protection of NADPH-Depleted Oligodendrocyte Precursor Cells Is Dependent on Supply of Reduced Glutathione

    PubMed Central

    Kilanczyk, Ewa; Saraswat Ohri, Sujata; Whittemore, Scott R.

    2016-01-01

    The pentose phosphate pathway is the main source of NADPH, which by reducing oxidized glutathione, contributes to antioxidant defenses. Although oxidative stress plays a major role in white matter injury, significance of NADPH for oligodendrocyte survival has not been yet investigated. It is reported here that the NADPH antimetabolite 6-amino-NADP (6AN) was cytotoxic to cultured adult rat spinal cord oligodendrocyte precursor cells (OPCs) as well as OPC-derived oligodendrocytes. The 6AN-induced necrosis was preceded by increased production of superoxide, NADPH depletion, and lower supply of reduced glutathione. Moreover, survival of NADPH-depleted OPCs was improved by the antioxidant drug trolox. Such cells were also protected by physiological concentrations of the neurosteroid dehydroepiandrosterone (10−8 M). The protection by dehydroepiandrosterone was associated with restoration of reduced glutathione, but not NADPH, and was sensitive to inhibition of glutathione synthesis. A similar protective mechanism was engaged by the cAMP activator forskolin or the G protein-coupled estrogen receptor (GPER/GPR30) ligand G1. Finally, treatment with the glutathione precursor N-acetyl cysteine reduced cytotoxicity of 6AN. Taken together, NADPH is critical for survival of OPCs by supporting their antioxidant defenses. Consequently, injury-associated inhibition of the pentose phosphate pathway may be detrimental for the myelination or remyelination potential of the white matter. Conversely, steroid hormones and cAMP activators may promote survival of NADPH-deprived OPCs by increasing a NADPH-independent supply of reduced glutathione. Therefore, maintenance of glutathione homeostasis appears as a critical effector mechanism for OPC protection against NADPH depletion and preservation of the regenerative potential of the injured white matter. PMID:27449129

  2. Antioxidant Protection of NADPH-Depleted Oligodendrocyte Precursor Cells Is Dependent on Supply of Reduced Glutathione.

    PubMed

    Kilanczyk, Ewa; Saraswat Ohri, Sujata; Whittemore, Scott R; Hetman, Michal

    2016-08-01

    The pentose phosphate pathway is the main source of NADPH, which by reducing oxidized glutathione, contributes to antioxidant defenses. Although oxidative stress plays a major role in white matter injury, significance of NADPH for oligodendrocyte survival has not been yet investigated. It is reported here that the NADPH antimetabolite 6-amino-NADP (6AN) was cytotoxic to cultured adult rat spinal cord oligodendrocyte precursor cells (OPCs) as well as OPC-derived oligodendrocytes. The 6AN-induced necrosis was preceded by increased production of superoxide, NADPH depletion, and lower supply of reduced glutathione. Moreover, survival of NADPH-depleted OPCs was improved by the antioxidant drug trolox. Such cells were also protected by physiological concentrations of the neurosteroid dehydroepiandrosterone (10(-8) M). The protection by dehydroepiandrosterone was associated with restoration of reduced glutathione, but not NADPH, and was sensitive to inhibition of glutathione synthesis. A similar protective mechanism was engaged by the cAMP activator forskolin or the G protein-coupled estrogen receptor (GPER/GPR30) ligand G1. Finally, treatment with the glutathione precursor N-acetyl cysteine reduced cytotoxicity of 6AN. Taken together, NADPH is critical for survival of OPCs by supporting their antioxidant defenses. Consequently, injury-associated inhibition of the pentose phosphate pathway may be detrimental for the myelination or remyelination potential of the white matter. Conversely, steroid hormones and cAMP activators may promote survival of NADPH-deprived OPCs by increasing a NADPH-independent supply of reduced glutathione. Therefore, maintenance of glutathione homeostasis appears as a critical effector mechanism for OPC protection against NADPH depletion and preservation of the regenerative potential of the injured white matter. PMID:27449129

  3. Pío del Río Hortega and the discovery of the oligodendrocytes

    PubMed Central

    Pérez-Cerdá, Fernando; Sánchez-Gómez, María Victoria; Matute, Carlos

    2015-01-01

    Pío del Río Hortega (1882–1945) discovered microglia and oligodendrocytes (OLGs), and after Ramón y Cajal, was the most prominent figure of the Spanish school of neurology. He began his scientific career with Nicolás Achúcarro from whom he learned the use of metallic impregnation techniques suitable to study non-neuronal cells. Later on, he joined Cajal’s laboratory. and Subsequently, he created his own group, where he continued to develop other innovative modifications of silver staining methods that revolutionized the study of glial cells a century ago. He was also interested in neuropathology and became a leading authority on Central Nervous System (CNS) tumors. In parallel to this clinical activity, del Río Hortega rendered the first systematic description of a major polymorphism present in a subtype of macroglial cells that he named as oligodendroglia and later OLGs. He established their ectodermal origin and suggested that they built the myelin sheath of CNS axons, just as Schwann cells did in the periphery. Notably, he also suggested the trophic role of OLGs for neuronal functionality, an idea that has been substantiated in the last few years. Del Río Hortega became internationally recognized and established an important neurohistological school with outstanding pupils from Spain and abroad, which nearly disappeared after his exile due to the Spanish civil war. Yet, the difficulty of metal impregnation methods and their variability in results, delayed for some decades the confirmation of his great insights into oligodendrocyte biology until the development of electron microscopy and immunohistochemistry. This review aims at summarizing the pioneer and essential contributions of del Río Hortega to the current knowledge of oligodendrocyte structure and function, and to provide a hint of the scientific personality of this extraordinary and insufficiently recognized man. PMID:26217196

  4. Correction of brain oligodendrocytes by AAVrh.10 intracerebral gene therapy in metachromatic leukodystrophy mice.

    PubMed

    Piguet, Françoise; Sondhi, Dolan; Piraud, Monique; Fouquet, Françoise; Hackett, Neil R; Ahouansou, Ornella; Vanier, Marie-Thérèse; Bieche, Ivan; Aubourg, Patrick; Crystal, Ronald G; Cartier, Nathalie; Sevin, Caroline

    2012-08-01

    Metachromatic leukodystrophy (MLD) is a lysosomal storage disorder characterized by accumulation of sulfatides in glial cells and neurons, the result of an inherited deficiency of arylsulfatase A (ARSA; EC 3.1.6.8) and myelin degeneration in the central and peripheral nervous systems. No effective treatment is currently available for the most frequent late infantile (LI) form of MLD, which results in rapid neurological degradation and early death after the onset of clinical manifestations. To potentially arrest or reverse disease progression, ARSA enzyme must be rapidly delivered to brain oligodendrocytes of patients with LI MLD. We previously showed that brain gene therapy with adeno-associated virus serotype 5 (AAV5) driving the expression of human ARSA cDNA under the control of the murine phosphoglycerate kinase (PGK) promoter alleviated most long-term disease manifestations in MLD mice. Herein, we evaluated the short-term effects of AAVrh.10 driving the expression of human ARSA cDNA under the control of the cytomegalovirus/β-actin hybrid (CAG/cu) promoter in 8-month-old MLD mice that already show marked sulfatide accumulation and brain pathology. Within 2 months, and in contrast to results with the AAV5-PGK-ARSA vector, a single intrastriatal injection of AAVrh.10cuARSA resulted in correction of brain sulfatide storage, accumulation of specific sulfatide species in oligodendrocytes, and associated brain pathology in the injected hemisphere. Better potency of the AAVrh.10cuARSA vector was mediated by higher neuronal and oligodendrocyte transduction, axonal transport of the AAVrh.10 vector and ARSA enzyme, as well as higher CAG/cu promoter driven expression of ARSA enzyme. These results strongly support the use of AAVrh.10cuARSA vector for intracerebral gene therapy in rapidly progressing early-onset forms of MLD. PMID:22642214

  5. Inhibition of Epidermal Growth Factor Receptor Improves Myelination and Attenuates Tissue Damage of Spinal Cord Injury.

    PubMed

    Zhang, Si; Ju, Peijun; Tjandra, Editha; Yeap, Yeeshan; Owlanj, Hamed; Feng, Zhiwei

    2016-10-01

    Preventing demyelination and promoting remyelination of denuded axons are promising therapeutic strategies for spinal cord injury (SCI). Epidermal growth factor receptor (EGFR) inhibition was reported to benefit the neural functional recovery and the axon regeneration after SCI. However, its role in de- and remyelination of axons in injured spinal cord is unclear. In the present study, we evaluated the effects of EGFR inhibitor, PD168393 (PD), on the myelination in mouse contusive SCI model. We found that expression of myelin basic protein (MBP) in the injured spinal cords of PD treated mice was remarkably elevated. The density of glial precursor cells and oligodendrocytes (OLs) was increased and the cell apoptosis in lesions was attenuated after PD168393 treatment. Moreover, PD168393 treatment reduced both the numbers of OX42 + microglial cells and glial fibrillary acidic protein + astrocytes in damaged area of spinal cords. We thus conclude that the therapeutic effects of EGFR inhibition after SCI involves facilitating remyelination of the injured spinal cord, increasing of oligodendrocyte precursor cells and OLs, as well as suppressing the activation of astrocytes and microglia/macrophages. PMID:26883518

  6. Potential Benefit of the Charge-Stabilized Nanostructure Saline RNS60 for Myelin Maintenance and Repair.

    PubMed

    Rao, Vijayaraghava T S; Khan, Damla; Jones, Russell G; Nakamura, Diane S; Kennedy, Timothy E; Cui, Qiao-Ling; Rone, Malena B; Healy, Luke M; Watson, Richard; Ghosh, Supurna; Antel, Jack P

    2016-01-01

    Myelin injury in multiple sclerosis (MS) has been attributed both to "outside-in" primary immune mediated and "inside-out" metabolic stress of oligodendrocyte (OL) related mechanisms. Subsequent remyelination is dependent on recruitment and differentiation of oligodendrocyte progenitor cells (OPCs). RNS60 is a physically-modified saline containing charge-stabilized nanobubbles generated by subjecting normal saline to Taylor-Couette-Poiseuille (TCP) flow under elevated oxygen pressure. Administration of RNS60 has been shown to reduce the severity of EAE by dampening the immune response and myelin loss. Additionally, RNS60 has been demonstrated to enhance mitochondrial ATP synthesis in neurons. Here, we used post-natal rat derived OLs and OPCs to assess the impact of RNS60 on the response of OLs to metabolic stress in vitro (glucose-nutrient deprivation, referred to as 'NG') and on OPC differentiation capacity. Under the NG condition, our findings indicate that RNS60 decreases caspases 3/7 activation. Respirometric analyses revealed that RNS60 increased spare glycolytic capacity (SGC) under normal culture conditions. However, RNS60 enhanced OL spare respiratory capacity (SRC) when a metabolic stress was present. Furthermore, we show that RNS60 promotes OPC differentiation under physiological conditions. Our findings provide evidence for the potential therapeutic efficacy of RNS60 through the promotion of OL survival and OPC differentiation. PMID:27451946

  7. Potential Benefit of the Charge-Stabilized Nanostructure Saline RNS60 for Myelin Maintenance and Repair

    PubMed Central

    Rao, Vijayaraghava T. S.; Khan, Damla; Jones, Russell G.; Nakamura, Diane S.; Kennedy, Timothy E.; Cui, Qiao-Ling; Rone, Malena B.; Healy, Luke M.; Watson, Richard; Ghosh, Supurna; Antel, Jack P.

    2016-01-01

    Myelin injury in multiple sclerosis (MS) has been attributed both to “outside-in” primary immune mediated and “inside-out” metabolic stress of oligodendrocyte (OL) related mechanisms. Subsequent remyelination is dependent on recruitment and differentiation of oligodendrocyte progenitor cells (OPCs). RNS60 is a physically-modified saline containing charge-stabilized nanobubbles generated by subjecting normal saline to Taylor-Couette-Poiseuille (TCP) flow under elevated oxygen pressure. Administration of RNS60 has been shown to reduce the severity of EAE by dampening the immune response and myelin loss. Additionally, RNS60 has been demonstrated to enhance mitochondrial ATP synthesis in neurons. Here, we used post-natal rat derived OLs and OPCs to assess the impact of RNS60 on the response of OLs to metabolic stress in vitro (glucose-nutrient deprivation, referred to as ‘NG’) and on OPC differentiation capacity. Under the NG condition, our findings indicate that RNS60 decreases caspases 3/7 activation. Respirometric analyses revealed that RNS60 increased spare glycolytic capacity (SGC) under normal culture conditions. However, RNS60 enhanced OL spare respiratory capacity (SRC) when a metabolic stress was present. Furthermore, we show that RNS60 promotes OPC differentiation under physiological conditions. Our findings provide evidence for the potential therapeutic efficacy of RNS60 through the promotion of OL survival and OPC differentiation. PMID:27451946

  8. SncRNA715 Inhibits Schwann Cell Myelin Basic Protein Synthesis

    PubMed Central

    Müller, Christina; Hochhaus, Nina M.; Fontana, Xavier; Luhmann, Heiko J.; White, Robin

    2015-01-01

    Myelin basic proteins (MBP) are major constituents of the myelin sheath in the central nervous system (CNS) and the peripheral nervous system (PNS). In the CNS Mbp translation occurs locally at the axon-glial contact site in a neuronal activity-dependent manner. Recently we identified the small non-coding RNA 715 (sncRNA715) as a key inhibitor of Mbp translation during transport in oligodendrocytes. Mbp mRNA localization in Schwann cells has been observed, but has not been investigated in much detail. Here we could confirm translational repression of Mbp mRNA in Schwann cells. We show that sncRNA715 is expressed and its levels correlate inversely with MBP in cultured Schwann cells and in the sciatic nerve in vivo. Furthermore we could reduce MBP protein levels in cultured Schwann cells by increasing the levels of the inhibitory sncRNA715. Our findings suggest similarities in sncRNA715-mediated translational repression of Mbp mRNA in oligodendrocytes and Schwann cells. PMID:26317513

  9. SncRNA715 Inhibits Schwann Cell Myelin Basic Protein Synthesis.

    PubMed

    Müller, Christina; Hochhaus, Nina M; Fontana, Xavier; Luhmann, Heiko J; White, Robin

    2015-01-01

    Myelin basic proteins (MBP) are major constituents of the myelin sheath in the central nervous system (CNS) and the peripheral nervous system (PNS). In the CNS Mbp translation occurs locally at the axon-glial contact site in a neuronal activity-dependent manner. Recently we identified the small non-coding RNA 715 (sncRNA715) as a key inhibitor of Mbp translation during transport in oligodendrocytes. Mbp mRNA localization in Schwann cells has been observed, but has not been investigated in much detail. Here we could confirm translational repression of Mbp mRNA in Schwann cells. We show that sncRNA715 is expressed and its levels correlate inversely with MBP in cultured Schwann cells and in the sciatic nerve in vivo. Furthermore we could reduce MBP protein levels in cultured Schwann cells by increasing the levels of the inhibitory sncRNA715. Our findings suggest similarities in sncRNA715-mediated translational repression of Mbp mRNA in oligodendrocytes and Schwann cells. PMID:26317513

  10. Myelination in vitro of rodent dorsal root ganglia by glial progenitor cells.

    PubMed

    Zajicek, J; Compston, A

    1994-12-01

    Oligodendrocytes synthesize myelin in the mammalian central nervous system; they develop from glial progenitors which, at least in vitro, are bipotential and also differentiate into astrocytes. Maturation of these O-2A progenitors is known to be influenced by growth factors and by extracellular matrix molecules. We investigated the effect of neurons on glial development by co-culturing highly purified rodent embryonic dorsal root ganglia with neonatal O-2A progenitors. Neurons produce signals, including platelet-derived growth factor BB and basic fibroblast growth factor, which stimulate progenitor cells to synthesize DNA; axonal contact is associated with down-regulation in the expression of complex ganglioside surface molecules on O-2A progenitors; with maturation, many of these cells develop into oligodendrocytes allowing the normal process of myelination to take place, but neurons also promote the differentiation of type 2 astrocytes. This orchestration of proliferation and differentiation in O-2A progenitor cells favours the development of glial-neuronal interactions needed for saltatory conduction of the nerve impulse. PMID:7820570

  11. Krabbe disease: involvement of connexin43 in the apoptotic effects of sphingolipid psychosine on mouse oligodendrocyte precursors.

    PubMed

    Graziano, A C E; Parenti, R; Avola, R; Cardile, V

    2016-01-01

    Krabbe disease is a genetic demyelinating syndrome characterized by deficiency of the enzyme β-galactosylceramidase, lysosomal psychosine accumulation, and loss of myelin-forming cells. In this study, some apoptotic markers such as apoptotic index (AI), DNA fragmentation, caspase-3, PTEN, Bad, and PI3K were determined in oligodendrocyte precursors from wild type or twitcher mice untreated or treated with psychosine. Twitcher is a natural mouse model of Krabbe disease containing a premature stop codon (W339X) in the β-galactosylceramidase gene. Moreover, a possible involvement of connexin (Cx)43 in cell death of oligodendrocyte precursors induced by psychosine was investigated with the final aim to provide a contribution to the knowledge of the molecular mechanisms and pathophysiological events that occur in Krabbe disease. Connexins are a multigene family of structurally related trans-membrane proteins able to modulate essential cellular processes such as proliferation, differentiation and migration. Among these, Cx43 is the predominant isoform in many cell types, including neural progenitor cells. Our results showed an increase of AI, DNA fragmentation, caspase-3, PTEN, Bad, and Cx43 associated to a decrease of PI3K, pAKT and pBad. Taken together, these findings suggest an involvement of Cx43 in the psychosine-mediated apoptosis of primary oligodendrocyte progenitors from wild type or twitcher mice, used for the first time as cell models in comparison. It could open unexplored perspective also for other demyelinating diseases. PMID:26459425

  12. Axolemmal abnormalities in myelin mutants.

    PubMed

    Rosenbluth, J

    1990-01-01

    Evidence is reviewed that the paranodal axoglial junction plays important roles in the differentiation and function of myelinated axons. In myelin-deficient axons, ion flux across the axolemma is greater than that in myelinated fibers because a larger proportion of the axolemma is active during continuous, as opposed to saltatory, conduction. In addition, older myelin-deficient rats that have developed spontaneous seizures display small foci of node-like E-face particle accumulations in CNS axons as well as more diffuse regions of increased particle density and number. Assuming that the E-face particles represent sodium channels, such regions could underlie high sodium current density during activity, low threshold for excitation, and increased extracellular potassium accumulation. Depending on the degree of spontaneous channel opening, they could also represent sites of spontaneous generation of activity. The appearance of seizures and their gradual increase in frequency and severity could represent an increase in the number of such regions. In addition, diminution in the dimensions of the extracellular space during maturation would result in increased extracellular resistance, which, together with increasing axonal diameter, would tend to increase the likelihood of ephaptic interaction among neighboring axons as well as the likelihood of extracellular potassium rises to levels that could cause spontaneous activity. PMID:2268117

  13. Clobetasol and Halcinonide Act as Smoothened Agonists to Promote Myelin Gene Expression and RxRγ Receptor Activation

    PubMed Central

    De Nardis, Velia; Di Giandomenico, Daniele; Lucisano, Giuseppe; Scardapane, Marco; Poma, Anna; Ragnini-Wilson, Antonella

    2015-01-01

    One of the causes of permanent disability in chronic multiple sclerosis patients is the inability of oligodendrocyte progenitor cells (OPCs) to terminate their maturation program at lesions. To identify key regulators of myelin gene expression acting at the last stages of OPC maturation we developed a drug repositioning strategy based on the mouse immortalized oligodendrocyte (OL) cell line Oli-neu brought to the premyelination stage by stably expressing a key factor regulating the last stages of OL maturation. The Prestwick Chemical Library® of 1,200 FDA-approved compound(s) was repositioned at three dosages based on the induction of Myelin Basic Protein (MBP) expression. Drug hits were further validated using dosage-dependent reproducibility tests and biochemical assays. The glucocorticoid class of compounds was the most highly represented and we found that they can be divided in three groups according to their efficacy on MBP up-regulation. Since target identification is crucial before bringing compounds to the clinic, we searched for common targets of the primary screen hits based on their known chemical-target interactomes, and the pathways predicted by top ranking compounds were validated using specific inhibitors. Two of the top ranking compounds, Halcinonide and Clobetasol, act as Smoothened (Smo) agonists to up-regulate myelin gene expression in the Oli-neuM cell line. Further, RxRγ activation is required for MBP expression upon Halcinonide and Clobetasol treatment. These data indicate Clobetasol and Halcinonide as potential promyelinating drugs and also provide a mechanistic understanding of their mode of action in the pathway leading to myelination in OPCs. Furthermore, our classification of glucocorticoids with respect to MBP expression provides important novel insights into their effects in the CNS and a rational criteria for their choice in combinatorial therapies in de-myelinating diseases. PMID:26658258

  14. Myelin Loss Does Not Lead to Axonal Degeneration in a Long-Lived Model of Chronic Demyelination

    PubMed Central

    Smith, Chelsey M.; Cooksey, Elizabeth; Duncan, Ian D.

    2014-01-01

    Current dogma suggests that chronically demyelinated axons are at risk for degeneration, with axonal loss resulting in permanent disability in myelin disease. However, the trophic role of the myelin sheath in long-term axonal survival is incompletely understood. Previous observations of the effect of dysmyelination or demyelination on axonal survival in the myelin mutants has been limited because of their short life span. In this study, we used the Long–Evans shaker (les) rat, which can live up to 9 months, to study axonal health and survival after chronic demyelination. At 2 weeks, ~29% of medium and ~47% of large fiber axons are myelinated in les spinal cord. However, by 3 months, no medium and ~<1% of large-diameter axons retain myelin. After demyelination, axons have a reduced-caliber, abnormal neurofilament distribution and an increase in mitochondrial number. However, there are no signs of axonal degeneration in les rats up to 9 months. Instead, there is a profound increase in oligodendrocytes, which were found to express BDNF, NT-3, and IGF-1. Importantly, this study provides in vivo evidence that mature glial cells produce various neurotrophic factors that may aid in the survival of axons after chronic demyelination. PMID:23392698

  15. The Deterioration Seen in Myelin Related Morphophysiology in Vanadium Exposed Rats is Partially Protected by Concurrent Iron Deficiency.

    PubMed

    Usende, Ifukibot Levi; Leitner, Dominque F; Neely, Elizabeth; Connor, James R; Olopade, James O

    2016-01-01

    Oligodendrocyte development and myelination occurs vigorously during the early post natal period which coincides with the period of peak mobilization of iron. Oligodendrocyte progenitor cells (OPCs) are easily disturbed by any agent that affects iron homeostasis and its assimilation into these cells. Environmental exposure to vanadium, a transition metal can disrupt this iron homeostasis. We investigated the interaction of iron deficiency and vanadium exposure on the myelination infrastructure and its related neurobehavioural phenotypes, and neurocellular profiles in developing rat brains. Control group (C) dams were fed normal diet while Group 2 (V) dams were fed normal diet and pups were injected with 3mg/kg body weight of sodium metavanadate daily from postnatal day (PND) 1-21. Group 3 (I+V) dams were fed iron deficient diet after delivery and pups injected with 3mg/kg body weight sodium metavanadate from PND1-21. Body and brain weights deteriorated in I+V relative to C and V while neurobehavioral deficit occurred more in V. Whereas immunohistochemical staining shows more astrogliosis and microgliosis indicative of neuroinflammation in I+V, more intense OPCs depletion and hypomyelination were seen in the V, and this was partially protected in I+V. In in vitro studies, vanadium induced glial cells toxicity was partially protected only at the LD 50 dose with the iron chelator, desferroxamine. The data indicate that vanadium promotes myelin damage and iron deficiency in combination with vanadium partially protects this neurotoxicological effects of vanadium. PMID:27574759

  16. Oxidized phosphatidylcholine formation and action in oligodendrocytes

    PubMed Central

    Qin, Jingdong; Testai, Fernando D; Dawson, Sylvia; Kilkus, John; Dawson, Glyn

    2010-01-01

    Reactive oxygen species play a major role in neurodegeneration. Increasing concentrations of peroxide induce neural cell death through activation of pro-apoptotic pathways. We now report that hydrogen peroxide generated sn-2 oxidized phosphatidylcholine (OxPC) in neonatal rat oligodendrocytes and that synthetic oxidized phosphatidylcholine (1-palmitoyl-2-(5′-oxo)valeryl-sn-glycero-3 phosphorylcholine, POVPC) also induced apoptosis in neonatal rat oligodendrocytes. POVPC activated caspases 3 and 8, and neutral sphingomyelinase (NSMase), but not acid sphingomyelinase. Downstream pro-apoptotic pathways activated by POVPC treatment included the Jun N-terminal kinase (JNK) proapoptotic cascade and the degradation of phospho-Akt. Activation of NSMase occurred within 1h, was blocked by inhibitors of caspase 8, increased mainly C18 and C24:1-ceramides, and appeared to be concentrated in detergent-resistant microdomains (Rafts). We conclude that OxPC initially activates NSMase and converts sphingomyelin into ceramide, to mediate a series of downstream pro-apoptotic events in oligodendrocytes. PMID:19545281

  17. Release of arachidonic acid from oligodendrocytes by terminal complement proteins, C5b-C9

    SciTech Connect

    Shirazi, Y.; Imagawa, D.K.; Shin, M.L.

    1986-03-01

    Activation of C5b-C9 on monocytes, macrophages, platelets and neutrophils induces membrane lipid hydrolysis and generates arachidonic acid (AA) and its oxygenated derivatives. Additionally, activation of C5b-C9 and myelin lipid hydrolysis has been observed in demyelination. The authors have investigated the modulatory effect of C5b-9 on membrane lipid hydrolysis of oligodendrocytes (OLG), the myelin producing cells in the central nervous system. Antibody-sensitized rat OLG, prelabeled with /sup 14/C AA were treated with excess C6-deficient rabbit serum reconstituted with limiting doses of C6. Qualitative analysis of the supernatants by HPLC revealed the presence of both cyclooxygenase and lipooxygenase products. Prostaglandin E/sub 2/, leukotriene (LT) E/sub 4/, LTB/sub 4/ and free AA were the major radiolabeled products. The kinetics and dose response of LTB/sub 4/ release with respect to the cytolytic dose of C5b-9 were quantitated by radioimmunoassay. LTB/sub 4/ release approached maximum in 1 hr and higher amounts were detected with fewer C5b-9 channels. Addition of C8 to OLG bearing C5b-7 intermediates induced maximum LTB/sub 4/ release without further enhancement by C9 in contrast to the absolute requirement of C9 in mediator release from rat neutrophils. Thus, the requirement of C5b-8 or C5b-9 in mediator release appears to be cell-type dependent.

  18. Myelin synthesis in the peripheral nervous system.

    PubMed

    Garbay, B; Heape, A M; Sargueil, F; Cassagne, C

    2000-06-01

    By imposing saltatory conduction on the nervous impulse, the principal role of the myelin sheath is to allow the faster propagation of action potentials along the axons which it surrounds. Peripheral nervous system (PNS) myelin is formed by the differentiation of the plasma membrane of Schwann cells. One of the biochemical characteristics that distinguishes myelin from other biological membranes is its high lipid-to-protein ratio. All the major lipid classes are represented in the myelin membrane, while several myelin-specific proteins have been identified. During development, the presence of axons is required for the initiation of myelination, but the nature of the axonal signal is still unknown. The only certainties are that this signal is synthesized by axons whose diameter is greater than 0.7 microm, and that the signal(s) include(s) a diffusible molecule. Morphological studies have provided us with information concerning the timing of myelination, the mechanism by which immature Schwann cells differentiate into a myelinating phenotype and lay down the myelin sheath around the axon, and the accumulation and the structure of the myelin membrane. The last 20 years have seen the identification and the cDNA and gene cloning of the major PNS myelin proteins, which signalled the beginning of the knock-out decade: transgenic null-mutant mice have been created for almost every protein gene. The study of these animals shows that the formation of myelin is considerably less sensitive to molecular alterations than the maintenance of myelin. During the same period, important data has been gathered concerning the synthesis and function of lipids in PNS myelin, although this field has received relatively little attention compared with that of their protein counterparts. PMID:10727776

  19. The neural androgen receptor: a therapeutic target for myelin repair in chronic demyelination.

    PubMed

    Hussain, Rashad; Ghoumari, Abdel M; Bielecki, Bartosz; Steibel, Jérôme; Boehm, Nelly; Liere, Philippe; Macklin, Wendy B; Kumar, Narender; Habert, René; Mhaouty-Kodja, Sakina; Tronche, François; Sitruk-Ware, Regine; Schumacher, Michael; Ghandour, M Said

    2013-01-01

    Myelin regeneration is a major therapeutic goal in demyelinating diseases, and the failure to remyelinate rapidly has profound consequences for the health of axons and for brain function. However, there is no efficient treatment for stimulating myelin repair, and current therapies are limited to anti-inflammatory agents. Males are less likely to develop multiple sclerosis than females, but often have a more severe disease course and reach disability milestones at an earlier age than females, and these observations have spurred interest in the potential protective effects of androgens. Here, we demonstrate that testosterone treatment efficiently stimulates the formation of new myelin and reverses myelin damage in chronic demyelinated brain lesions, resulting from the long-term administration of cuprizone, which is toxic for oligodendrocytes. In addition to the strong effect of testosterone on myelin repair, the number of activated astrocytes and microglial cells returned to low control levels, indicating a reduction of neuroinflammatory responses. We also identify the neural androgen receptor as a novel therapeutic target for myelin recovery. After the acute demyelination of cerebellar slices in organotypic culture, the remyelinating actions of testosterone could be mimicked by 5α-dihydrotestosterone, a metabolite that is not converted to oestrogens, and blocked by the androgen receptor antagonist flutamide. Testosterone treatment also failed to promote remyelination after chronic cuprizone-induced demyelination in mice with a non-functional androgen receptor. Importantly, testosterone did not stimulate the formation of new myelin sheaths after specific knockout of the androgen receptor in neurons and macroglial cells. Thus, the neural brain androgen receptor is required for the remyelination effect of testosterone, whereas the presence of the receptor in microglia and in peripheral tissues is not sufficient to enhance remyelination. The potent synthetic

  20. Structure and Expression of Myelin Basic Protein Gene Sequences in the mld Mutant Mouse: Reiteration and Rearrangement of the Mbp Gene

    PubMed Central

    Akowitz, Alfred A.; Barbarese, Elisa; Scheld, Kathy; Carson, John H.

    1987-01-01

    The mld mutation on chromosome 18 in the mouse is a putative allele of the shiverer (shi) mutation. We have analyzed the structure of myelin basic protein (MBP) gene sequences in mld DNA by restriction mapping of genomic DNA. The results indicate that the mld chromosome carries two copies of the MBP structural gene, one of which is intact and one of which is interrupted. Genetic analysis indicates that the interrupted gene is close to the intact MBP structural gene and cosegregates with the mld mutation. We have also analyzed the levels of MBP polypeptides and MBP-specific mRNA in wild-type, homozygous and heterozygous shiverer and mld mice and in mice carrying both mutations. The results indicate that both shi and mld are cis-acting codominant mutations that cause severely reduced steady state levels of MBP-specific mRNA and MBP polypeptides in the brain. We have analyzed the total number of oligodendrocytes and the number of MBP-positive oligodendrocytes in mld and shi brain primary cultures. In shi cultures, none of the oligodendrocytes expresses MBP. However, in mld cultures, approximately 5% of the oligodendrocytes express MBP. The nature of the "revertant" mld oligodendrocytes is not known. PMID:2440764

  1. Glycosylation Engineering of Glycoproteins

    NASA Astrophysics Data System (ADS)

    Sadamoto, Reiko; Nishimura, Shin-Ichiro

    Naturally occurring glycosylation of glycoproteins varies in glycosylation site and in the number and structure of glycans. The engineering of well-defined glycoproteins is an important technology for the preparation of pharmaceutically relevant glycoproteins and in the study of the relationship between glycans and proteins on a structure-function level. In pharmaceutical applications of glycoproteins, the presence of terminal sialic acids on glycans is particularly important for the in vivo circulatory half life, since sialic acid-terminated glycans are not recognized by asialoglycoprotein receptors. Therefore, there have been a number of attempts to control or modify cellular metabolism toward the expression of glycoproteins with glycosylation profiles similar to that of human glycoproteins. In this chapter, recent methods for glycoprotein engineering in various cell culture systems (mammalian cells, plant, yeast, and E. coli) and advances in the chemical approach to glycoprotein formation are described.

  2. Peripheral myelin of Xenopus laevis: role of electrostatic and hydrophobic interactions in membrane compaction.

    PubMed

    Luo, XiaoYang; Cerullo, Jana; Dawli, Tamara; Priest, Christina; Haddadin, Zaid; Kim, Angela; Inouye, Hideyo; Suffoletto, Brian P; Avila, Robin L; Lees, Jonathan P B; Sharma, Deepak; Xie, Bo; Costello, Catherine E; Kirschner, Daniel A

    2008-04-01

    P0 glycoprotein is the major structural protein of peripheral nerve myelin where it is thought to modulate inter-membrane adhesion at both the extracellular apposition, which is labile upon changes in pH and ionic strength, and the cytoplasmic apposition, which is resistant to such changes. Most studies on P0 have focused on structure-function correlates in higher vertebrates. Here, we focused on its role in the structure and interactions of frog (Xenopus laevis) myelin, where it exists primarily in a dimeric form. As part of our study, we deduced the full sequence of X. laevis P0 (xP0) from its cDNA. The xP0 sequence was found to be similar to P0 sequences of higher vertebrates, suggesting that a common mechanism of PNS myelin compaction via P0 interaction might have emerged through evolution. As previously reported for mouse PNS myelin, a similar change of extracellular apposition in frog PNS myelin as a function of pH and ionic strength was observed, which can be explained by a conformational change of P0 due to protonation-deprotonation of His52 at P0's putative adhesive interface. On the other hand, the cytoplasmic apposition in frog PNS myelin, like that in the mouse, remained unchanged at different pH and ionic strength. The contribution of hydrophobic interactions to stabilizing the cytoplasmic apposition was tested by incubating sciatic nerves with detergents. Dramatic expansion at the cytoplasmic apposition was observed for both frog and mouse, indicating a common hydrophobic nature at this apposition. Urea also expanded the cytoplasmic apposition of frog myelin likely owing to denaturation of P0. Removal of the fatty acids that attached to the single Cys residue in the cytoplasmic domain of P0 did not change PNS myelin structure of either frog or mouse, suggesting that the P0-attached fatty acyl chain does not play a significant role in PNS myelin compaction and stability. These results help clarify the present understanding of P0's adhesion role and the

  3. Skin-derived neural precursors competitively generate functional myelin in adult demyelinated mice

    PubMed Central

    Mozafari, Sabah; Laterza, Cecilia; Roussel, Delphine; Bachelin, Corinne; Marteyn, Antoine; Deboux, Cyrille; Martino, Gianvito; Evercooren, Anne Baron-Van

    2015-01-01

    Induced pluripotent stem cell–derived (iPS-derived) neural precursor cells may represent the ideal autologous cell source for cell-based therapy to promote remyelination and neuroprotection in myelin diseases. So far, the therapeutic potential of reprogrammed cells has been evaluated in neonatal demyelinating models. However, the repair efficacy and safety of these cells has not been well addressed in the demyelinated adult CNS, which has decreased cell plasticity and scarring. Moreover, it is not clear if these induced pluripotent–derived cells have the same reparative capacity as physiologically committed CNS-derived precursors. Here, we performed a side-by-side comparison of CNS-derived and skin-derived neural precursors in culture and following engraftment in murine models of adult spinal cord demyelination. Grafted induced neural precursors exhibited a high capacity for survival, safe integration, migration, and timely differentiation into mature bona fide oligodendrocytes. Moreover, grafted skin–derived neural precursors generated compact myelin around host axons and restored nodes of Ranvier and conduction velocity as efficiently as CNS-derived precursors while outcompeting endogenous cells. Together, these results provide important insights into the biology of reprogrammed cells in adult demyelinating conditions and support use of these cells for regenerative biomedicine of myelin diseases that affect the adult CNS. PMID:26301815

  4. Mutation of the proteolipid protein gene PLP in a human X chromosome-linked myelin disorder.

    PubMed

    Hudson, L D; Puckett, C; Berndt, J; Chan, J; Gencic, S

    1989-10-01

    Myelin is a highly specialized membrane unique to the nervous system that ensheaths axons to permit the rapid saltatory conduction of impulses. The elaboration of a compact myelin sheath is disrupted in a diverse spectrum of human disorders, many of which are of unknown etiology. The X chromosome-linked human disorder Pelizaeus-Merzbacher disease is a clinically and pathologically heterogeneous group of disorders that demonstrate a striking failure of oligodendrocyte differentiation. This disease appears pathologically and genetically to be similar to the disorder seen in the dysmyelinating mouse mutant jimpy, which has a point mutation in the gene encoding an abundant myelin protein, proteolipid protein (PLP). We report that the molecular defect in one Pelizaeus-Merzbacher family is likewise a point mutation in the PLP gene. A single T----C transition results in the substitution of a charged amino acid residue, arginine, for tryptophan in one of the four extremely hydrophobic domains of the PLP protein. The identification of a mutation in this Pelizaeus-Merzbacher family should facilitate the molecular classification and diagnosis of these X chromosome-linked human dysmyelinating disorders. PMID:2479017

  5. Loss of Myelin Basic Protein Function Triggers Myelin Breakdown in Models of Demyelinating Diseases.

    PubMed

    Weil, Marie-Theres; Möbius, Wiebke; Winkler, Anne; Ruhwedel, Torben; Wrzos, Claudia; Romanelli, Elisa; Bennett, Jeffrey L; Enz, Lukas; Goebels, Norbert; Nave, Klaus-Armin; Kerschensteiner, Martin; Schaeren-Wiemers, Nicole; Stadelmann, Christine; Simons, Mikael

    2016-07-12

    Breakdown of myelin sheaths is a pathological hallmark of several autoimmune diseases of the nervous system. We employed autoantibody-mediated animal models of demyelinating diseases, including a rat model of neuromyelitis optica (NMO), to target myelin and found that myelin lamellae are broken down into vesicular structures at the innermost region of the myelin sheath. We demonstrated that myelin basic proteins (MBP), which form a polymer in between the myelin membrane layers, are targeted in these models. Elevation of intracellular Ca(2+) levels resulted in MBP network disassembly and myelin vesiculation. We propose that the aberrant phase transition of MBP molecules from their cohesive to soluble and non-adhesive state is a mechanism triggering myelin breakdown in NMO and possibly in other demyelinating diseases. PMID:27346352